Pass in position_ids into attention for GPT2

[jackzhxng]

What does this PR do?

Pass in position_ids so that the custom attention interface implementations have access to it.

Who can review?

@ArthurZucker @Cyrilvallez

[github-actions]

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

run-slow: gpt2

[vasqu]

We have a test for this but it is skipped with GPT2 currently, i.e. check if paddingfree is the same as padding which relies exactly on this. I have a PR for this over here #42848

The logic is sound tho, depending on the other PR, it might make more sense to add an explicit test here

[jackzhxng]

Sounds good, lmk if you want the test here / feel free to merge

[vasqu]

Could you add a small test here directly? My other PR is going a bit beyond what I had originally planned

[ArthurZucker]

Indeed let's add a test!

[HuggingFaceDocBuilderDev]

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[vasqu]

#42848 is now merged and includes the passing of the pos ids (along testing) so I'm closing this one - feel free to reopen or tag me if it does not work as expected