Mistral qna

[sriram-1]

What does this PR do?

Added a MistralForQuestionAnswering class to the modeling_mistral.py so Mistral models have AutoModelForQuestionAnswering support.

Fixes #28908

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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• Did you write any new necessary tests?

Who can review?

@ArthurZucker
Anyone in the community is free to review the PR once the tests have passed. Feel free to tag
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[ArthurZucker]

Thanks! As I usually say, let's first open a feature request for this, and if the community is eager to have it we'll merge! 🤗 there are not checkpoints available so not really usable as is

[sriram-1]

@ArthurZucker #28908 already feature request is tagged.

[ArthurZucker]

Then let's wait until:

• either community pushes for this
• there are good checkpoints for this model and task! 🥳

[github-actions]

This issue has been automatically marked as stale because it has not had recent activity. If you think this still needs to be addressed please comment on this thread.

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