Add OpenPangu-V2 Model

[YuChangHui]

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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• 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).
• Did you read the contributor guideline and the
  Pull Request checks?
• Was this discussed/approved via a Github issue or the forum? Please add a link
  to it if that's the case.
• Did you make sure to update the documentation with your changes according to the guidelines?
• Did you write any new necessary tests?

[github-actions]

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

run-slow: auto, openpangu_v2

[github-actions]

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CI recap

Dashboard: View test results in Grafana
Latest run: 28775134416:2
Result: failure | Jobs: 15 | Tests: 171,829 | Failures: 12 | Duration: 22h 55m

[Rocketknight1]

cc @ArthurZucker for text models