[WIP][Spyre-Next] SpyreRMSNorm tests

[sducouedic]

Description

Adds tests for SpyreRMSNorm CustomOp: it compares the spyre output with reference RMSNorm operator running on cpu.

Work in progress:
The test currently isn't passing, the output shape is different
AssertionError: The values for attribute 'shape' do not match: torch.Size([4096]) != torch.Size([1024, 4096]) Need to figure out if the bug is in SpyreRMSNorm implementation or in the test

Related Issues

Fixes #805

Test Plan

pytest tests/test_spyre_rmsnorm.py::test_spyre_rms_norm -xsv

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)

[github-actions]

👋 Hi! Thank you for contributing to vLLM support on Spyre.
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.

[sducouedic]

There is an alternative implementation: #837