[PyTorch] Fused dbias-cast-transpose in bias operation

[timmoon10]

Description

This PR modifies the bias operation (see the operation-based API in #707) so that it can launch a fused kernel for computing bgrad, FP8 dgrad, and FP8 dgrad transpose.

Once #1164 is merged, this could be extended to call a fused kernel for dgelu, bgrad, FP8 dgrad, and FP8 dgrad transpose. However, it may be better to defer that to a followup PR since it will require some infrastructure changes (e.g. we want to apply different fusions in the FP8 and non-FP8 cases).

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)
• 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 refractor

Changes

• Fused dbias-cast-transpose kernel in bias operation

Checklist:

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

[timmoon10]

/te-ci pytorch