[Model] Add Support for Grok2

[wenchen76]

Purpose

To address #23557

Test Plan

Test Result

This is a draft PR since the work is still in progress and the implementation currently produces incorrect results.

• Tokenizer support:
  tokenizer.tok.json is currently not supported. As a workaround, you can use the Hugging Face–compatible tokenizer available here:

• FlashAttention issue:
  I encountered the following error when testing:

RuntimeError: Worker failed with error 'This flash attention build does not support tanh softcapping.'

To work around this, I used flashinfer. I’m not sure if this error is specific to my environment.

• Response correctness:
  The generated responses are still incorrect, I haven’t had the chance to fully debug this yet.

@igor-susic1 @BranZhai @Crucifixion-Fxl — It would be great if you could take a look and help out whenever you get the chance. Thanks so much! 🙏

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Essential Elements of an Effective PR Description Checklist

• The purpose of the PR, such as "Fix some issue (link existing issues this PR will resolve)".
• The test plan, such as providing test command.
• The test results, such as pasting the results comparison before and after, or e2e results
• (Optional) The necessary documentation update, such as updating supported_models.md and examples for a new model.
• (Optional) Release notes update. If your change is user facing, please update the release notes draft in the Google Doc.

[mergify]

This pull request has merge conflicts that must be resolved before it can be
merged. Please rebase the PR, @wenchen76.

https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/working-with-forks/syncing-a-fork

[mergify]

This pull request has merge conflicts that must be resolved before it can be
merged. Please rebase the PR, @wenchen76.

https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/working-with-forks/syncing-a-fork

[mergify]

Documentation preview: https://vllm--24286.org.readthedocs.build/en/24286/

[reaganjlee]

Hey there, I'm curious on the status of this PR/if this description is still accurate?

[hmellor]

Closing this PR as Grok-2 support has been fully implemented and merged via #31847