[Kernel] Support MulAndSilu

[jeejeelee]

Currently there are 3 models in vllm that use this activation function: jais, ultravox and molmo. Implementing this kernel helps improve the performance of these models.

PS : It appears JAIS has different activation function choices, so keeping it unchanged for now.
ping @WoosukKwon @tlrmchlsmth

[github-actions]

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[comaniac]

IIRC we had this kernel before but removed, because of the introduction of torch compile?
cc @youkaichao

[mergify]

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

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

[jeejeelee]

IIRC we had this kernel before but removed, because of the introduction of torch compile? cc @youkaichao

@comaniac Thanks for your review. If there are other considerations that don't support this operator, I will close this PR, also cc @youkaichao