added Textnet fast image processor
Author: rahzaazhar
Pull request: yes

# What does this PR do?

Related [#36978](https://github.com/huggingface/transformers/issues/36978)
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Adds a fast image processor to the textnet model.  


## Before submitting
- [ ] This PR fixes a typo or improves the docs (you can dismiss the other checks if that's the case).
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      Pull Request section?
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- [ ] Did you write any new necessary tests?


## Who can review?

Anyone in the community is free to review the PR once the tests have passed. Feel free to tag
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Models:

- text models: @ArthurZucker
- vision models: @amyeroberts, @qubvel
- speech models: @eustlb
- graph models: @clefourrier

Library:

- flax: @gante and @Rocketknight1
- generate: @zucchini-nlp (visual-language models) or @gante (all others)
- pipelines: @Rocketknight1
- tensorflow: @gante and @Rocketknight1
- tokenizers: @ArthurZucker
- trainer: @zach-huggingface, @SunMarc and @qgallouedec
- chat templates: @Rocketknight1

Integrations:

- deepspeed: HF Trainer/Accelerate: @SunMarc @zach-huggingface
- ray/raytune: @richardliaw, @amogkam
- Big Model Inference: @SunMarc
- quantization (bitsandbytes, autogpt): @SunMarc @MekkCyber

Documentation: @stevhliu

HF projects:

- accelerate: [different repo](https://github.com/huggingface/accelerate)
- datasets: [different repo](https://github.com/huggingface/datasets)
- diffusers: [different repo](https://github.com/huggingface/diffusers)
- rust tokenizers: [different repo](https://github.com/huggingface/tokenizers)

Maintained examples (not research project or legacy):

- Flax: @Rocketknight1
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Comments:
cc @yonigozlan

Hi @yonigozlan thank you for your feedback, I've incorporated the changes you recommended. Some checks are failing not sure why. Let me know what I can do to pass these checks. Thanks!

**[For maintainers]** Suggested jobs to run (before merge)

run-slow: auto, textnet

The docs for this PR live [here](https://moon-ci-docs.huggingface.co/docs/transformers/pr_39884). All of your documentation changes will be reflected on that endpoint. The docs are available until 30 days after the last update.