[Feature] Enable FP32 RMSNorm

[bohnstingl]

Description

This PR enables the use of vLLM's native RMSNorm implementations.
We still need to keep our own custom OOT, as we need to enforce compilation.

Alternative to #742

Related Issues

#667 and #817

Test Plan

The behavior should be transparent to the user, so all existing tests should suffice.

Checklist

• I have read the contributing guidelines
• My code follows the project's code style (run bash format.sh)
• I have added tests for my changes (if applicable)
• I have updated the documentation (if applicable)
• My commits include a Signed-off-by: line (DCO compliance)

cc @yannicks1

[github-actions]

👋 Hi! Thank you for contributing.
Just a reminder: Make sure that your code passes all the linting checks, otherwise your PR won't be able to be merged. To do so, run ./format.sh.
Now you are good to go 🚀.

We also recommend installing prek and configuring it to check your code before every local commit.

[joerunde]

@bohnstingl it looks like there's still a test failure here, and then the way that the test fails seems to hold the card open causing the next couple tests to fail :(

I'd hope that fixing the behavior leading to the failing test would fix the card busy problem too, but seems like there's still work to do here?