Run Flake8 for nemo.export module
State: open | Pull request: yes

# What does this PR do ?

Run & apply [Flake8](https://flake8.pycqa.org/en/latest/) suggestions for nemo.export including (most common):
* [F541: f-string without any placeholders](https://docs.astral.sh/ruff/rules/f-string-missing-placeholders)
* [F841 local variable 'x' is assigned to but never used](https://www.flake8rules.com/rules/F841.html)
* [F401 'x' imported but unused](https://www.flake8rules.com/rules/F401.html)
* [E741 ambiguous variable name 'l']( https://www.flake8rules.com/rules/E741.html)
* [F821 undefined name 'x'](https://docs.astral.sh/ruff/rules/undefined-name)
* [E266 too many leading '#' for block comment](https://www.flake8rules.com/rules/E266.html)

**Collection**: NLP / LLM

# Usage

Flake8 command to diagnose issues (skipping selected ones):

```bash
flake8 nemo/export/ --ignore E203,W503,E501 --per-file-ignores="__init__.py:F401"
```

# GitHub Actions CI

The Jenkins CI system has been replaced by GitHub Actions self-hosted runners.

The GitHub Actions CI will run automatically when the "Run CICD" label is added to the PR.
To re-run CI remove and add the label again.
To run CI on an untrusted fork, a NeMo user with write access must first click "Approve and run".

# Before your PR is "Ready for review"
**Pre checks**:
- [ ] Make sure you read and followed [Contributor guidelines](https://github.com/NVIDIA/NeMo/blob/main/CONTRIBUTING.md)
- [ ] Did you write any new necessary tests?
- [ ] Did you add or update any necessary documentation?
- [ ] Does the PR affect components that are optional to install? (Ex: Numba, Pynini, Apex etc)
  - [ ] Reviewer: Does the PR have correct import guards for all optional libraries?
  
**PR Type**:
- [ ] New Feature
- [ ] Bugfix
- [ ] Documentation

If you haven't finished some of the above items you can still open "Draft" PR.


## Who can review?

Anyone in the community is free to review the PR once the checks have passed. 
[Contributor guidelines](https://github.com/NVIDIA/NeMo/blob/main/CONTRIBUTING.md) contains specific people who can review PRs to various areas.

# Additional Information
* Related to # (issue)


<!-- pylint-output-strict-mode-false -->

beep boop 🤖: 🙏 The following files have warnings. In case you are familiar with these, please try helping us to improve the code base.

---

Your code was analyzed with PyLint. The following annotations have been identified:

```
************* Module nemo.export.multimodal.build
nemo/export/multimodal/build.py:39:0: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/multimodal/build.py:73:0: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/multimodal/build.py:89:0: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/multimodal/build.py:115:0: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/multimodal/build.py:214:0: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/multimodal/build.py:241:4: C0115: Missing class docstring (missing-class-docstring)
nemo/export/multimodal/build.py:242:8: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/multimodal/build.py:250:8: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/multimodal/build.py:263:4: C0115: Missing class docstring (missing-class-docstring)
nemo/export/multimodal/build.py:270:8: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/multimodal/build.py:359:0: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/multimodal/build.py:377:4: C0115: Missing class docstring (missing-class-docstring)
nemo/export/multimodal/build.py:384:8: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/multimodal/build.py:436:0: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/multimodal/build.py:469:4: C0115: Missing class docstring (missing-class-docstring)
nemo/export/multimodal/build.py:477:8: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/multimodal/build.py:506:0: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/multimodal/build.py:521:0: C0116: Missing function or method docstring (missing-function-docstring)
************* Module nemo.export.sentencepiece_tokenizer
nemo/export/sentencepiece_tokenizer.py:236:0: C0301: Line too long (137/119) (line-too-long)
nemo/export/sentencepiece_tokenizer.py:55:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/sentencepiece_tokenizer.py:84:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/sentencepiece_tokenizer.py:113:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/sentencepiece_tokenizer.py:119:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/sentencepiece_tokenizer.py:138:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/sentencepiece_tokenizer.py:144:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/sentencepiece_tokenizer.py:153:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/sentencepiece_tokenizer.py:161:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/sentencepiece_tokenizer.py:186:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/sentencepiece_tokenizer.py:194:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/sentencepiece_tokenizer.py:202:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/sentencepiece_tokenizer.py:210:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/sentencepiece_tokenizer.py:217:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/sentencepiece_tokenizer.py:224:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/sentencepiece_tokenizer.py:231:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/sentencepiece_tokenizer.py:243:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/sentencepiece_tokenizer.py:253:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/sentencepiece_tokenizer.py:256:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/sentencepiece_tokenizer.py:263:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/sentencepiece_tokenizer.py:266:4: C0116: Missing function or method docstring (missing-function-docstring)
************* Module nemo.export.trt_llm.converter.model_converter
nemo/export/trt_llm/converter/model_converter.py:35:0: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/trt_llm/converter/model_converter.py:48:0: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/trt_llm/converter/model_converter.py:108:0: C0116: Missing function or method docstring (missing-function-docstring)
************* Module nemo.export.trt_llm.converter.model_to_trt_llm_ckpt
nemo/export/trt_llm/converter/model_to_trt_llm_ckpt.py:55:0: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/trt_llm/converter/model_to_trt_llm_ckpt.py:61:0: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/trt_llm/converter/model_to_trt_llm_ckpt.py:69:0: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/trt_llm/converter/model_to_trt_llm_ckpt.py:86:0: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/trt_llm/converter/model_to_trt_llm_ckpt.py:101:0: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/trt_llm/converter/model_to_trt_llm_ckpt.py:111:0: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/trt_llm/converter/model_to_trt_llm_ckpt.py:115:0: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/trt_llm/converter/model_to_trt_llm_ckpt.py:130:0: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/trt_llm/converter/model_to_trt_llm_ckpt.py:291:0: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/trt_llm/converter/model_to_trt_llm_ckpt.py:298:0: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/trt_llm/converter/model_to_trt_llm_ckpt.py:305:0: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/trt_llm/converter/model_to_trt_llm_ckpt.py:506:0: C0116: Missing function or method docstring (missing-function-docstring)
************* Module nemo.export.trt_llm.nemo_ckpt_loader.nemo_file
nemo/export/trt_llm/nemo_ckpt_loader/nemo_file.py:51:0: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/trt_llm/nemo_ckpt_loader/nemo_file.py:162:0: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/trt_llm/nemo_ckpt_loader/nemo_file.py:192:0: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/trt_llm/nemo_ckpt_loader/nemo_file.py:203:0: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/trt_llm/nemo_ckpt_loader/nemo_file.py:207:0: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/trt_llm/nemo_ckpt_loader/nemo_file.py:232:0: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/trt_llm/nemo_ckpt_loader/nemo_file.py:243:0: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/trt_llm/nemo_ckpt_loader/nemo_file.py:264:0: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/trt_llm/nemo_ckpt_loader/nemo_file.py:359:0: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/trt_llm/nemo_ckpt_loader/nemo_file.py:477:0: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/trt_llm/nemo_ckpt_loader/nemo_file.py:564:0: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/trt_llm/nemo_ckpt_loader/nemo_file.py:568:0: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/trt_llm/nemo_ckpt_loader/nemo_file.py:579:0: C0115: Missing class docstring (missing-class-docstring)
nemo/export/trt_llm/nemo_ckpt_loader/nemo_file.py:591:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/trt_llm/nemo_ckpt_loader/nemo_file.py:631:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/trt_llm/nemo_ckpt_loader/nemo_file.py:668:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/trt_llm/nemo_ckpt_loader/nemo_file.py:681:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/trt_llm/nemo_ckpt_loader/nemo_file.py:25:0: W0611: Unused import tensorstore (unused-import)
************* Module nemo.export.trt_llm.tensorrt_llm_build
nemo/export/trt_llm/tensorrt_llm_build.py:31:0: C0116: Missing function or method docstring (missing-function-docstring)
************* Module nemo.export.trt_llm.tensorrt_llm_run
nemo/export/trt_llm/tensorrt_llm_run.py:501:0: C0301: Line too long (124/119) (line-too-long)
nemo/export/trt_llm/tensorrt_llm_run.py:505:0: C0301: Line too long (135/119) (line-too-long)
nemo/export/trt_llm/tensorrt_llm_run.py:509:0: C0301: Line too long (123/119) (line-too-long)
nemo/export/trt_llm/tensorrt_llm_run.py:552:0: C0301: Line too long (181/119) (line-too-long)
nemo/export/trt_llm/tensorrt_llm_run.py:836:0: C0301: Line too long (153/119) (line-too-long)
nemo/export/trt_llm/tensorrt_llm_run.py:519:0: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/trt_llm/tensorrt_llm_run.py:528:0: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/trt_llm/tensorrt_llm_run.py:586:0: C0116: Missing function or method docstring (missing-function-docstring)
************* Module nemo.export.utils.lora_converter
nemo/export/utils/lora_converter.py:29:0: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/utils/lora_converter.py:43:0: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/utils/lora_converter.py:51:0: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/utils/lora_converter.py:160:0: C0116: Missing function or method docstring (missing-function-docstring)
************* Module nemo.export.vllm.model_converters
nemo/export/vllm/model_converters.py:59:0: C0115: Missing class docstring (missing-class-docstring)
nemo/export/vllm/model_converters.py:122:0: C0115: Missing class docstring (missing-class-docstring)
nemo/export/vllm/model_converters.py:191:0: C0115: Missing class docstring (missing-class-docstring)
nemo/export/vllm/model_converters.py:268:0: C0115: Missing class docstring (missing-class-docstring)
************* Module nemo.export.vllm_exporter
nemo/export/vllm_exporter.py:38:0: C0116: Missing function or method docstring (missing-function-docstring)
nemo/export/vllm_exporter.py:429:4: C0116: Missing function or method docstring (missing-function-docstring)

-----------------------------------
Your code has been rated at 9.68/10
```

---

Mitigation guide:

* Add sensible and useful docstrings to functions and methods
* For trivial methods like getter/setters, consider adding `# pylint: disable=C0116` inside the function itself
* To disable multiple functions/methods at once, put a `# pylint: disable=C0116` before the first and a `# pylint: enable=C0116` after the last.

By applying these rules, we reduce the occurance of this message in future.

Thank you for improving NeMo's documentation!