Add OpenPangu-V2 Model
Author: YuChangHui
Pull request: yes

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# What does this PR do?

Fixes # (issue)
This PR primarily aims to add support for the OpenPangu-V2 series of models in inference. 

The submitted code includes the inference implementations for OpenPangu-V2 model, along with the corresponding configurations and tokenizers.

For unit testing, we added a single-sample test for the openpangu-v2 model using  openpangu/openPangu-2.0-Flash. 

This is my first PR submission. After carefully studying the Contribute to Transformers guide, I've modified my code to pass all make fixup checks.

I'd greatly appreciate any feedback if additional changes or improvements are needed - please don't hesitate to point them out!

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- [x] I confirm that this is not a pure code agent PR.

## Before submitting
- [ ] This PR fixes a typo or improves the docs (you can dismiss the other checks if that's the case).
- [x] Did you read the [contributor guideline](https://huggingface.co/docs/transformers/contributing) and the
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Comments:
cc @arthurzucker for text models

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### CI recap

**Dashboard:** [View test results in Grafana](https://transformers-ci.lor-e.huggingface.cool/d/pytest-observability-by-pr/pytest-observability-branch?var-pr=47093)
**Latest run:** [28836905488:2](https://github.com/huggingface/transformers/actions/runs/28836905488)
**Result:** `failure` | **Jobs:** 15 | **Tests:** 171,878 | **Failures:** 12 | **Duration:** 24h 22m

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Excuse me,  how should I proceed with getting this MR merged? @ArthurZucker @Cyrilvallez @vasqu

Thank you for your contribution 🤗!

## CI Security Gate — automatic approval blocked

This PR was **not** automatically approved for CI because the security gate failed.

**Possible reasons:**
- The PR touches 50 or more files — only PRs with fewer than 50 changed files are automatically approved
- A changed file is outside the allowed directories (`src/`, `tests/`, `docs/`, `utils/`), has a disallowed extension (only `.py`, `.txt`, `.md` permitted outside `tests/` and `docs/`), or is not `.md`/`.yml` inside `docs/`
- A new high-severity security issue was detected in the changed Python files (Bandit check)

See the [workflow run](https://github.com/huggingface/transformers/actions/runs/29475858887) for the exact violations.

A maintainer can review and manually approve CI if a finding is a false positive.

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

run-slow: auto, hunyuan_vl, openpangu_v2