[PyTorch Debug] NVFP4 debug stats support

[pggPL]

Description

This PR adds support for NVFP4 statistics: underflows and mse. I add them in seperate feature, because we may want to have a lot nvfp4-specific features added later.

Also, I renamed few variables from "fp8"-like to "quantization"-like. I cannot rename all of them - for example "is_fp8_gemm_enabled" which is an API call, so I left some of them.

Fixes # (issue)

Type of change

• [ ] Documentation change (change only to the documentation, either a fix or a new content)
• [ ] Bug fix (non-breaking change which fixes an issue)
• [x] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
• [ ] Infra/Build change
• [ ] Code refactoring

Checklist:

• [x] I have read and followed the contributing guidelines
• [x] The functionality is complete
• [x] I have commented my code, particularly in hard-to-understand areas
• [x] I have made corresponding changes to the documentation
• [x] My changes generate no new warnings
• [x] I have added tests that prove my fix is effective or that my feature works
• [x] New and existing unit tests pass locally with my changes

[pggPL]

/te-ci pytorch