Integrate KunLunXin TE-FL backend patches

[Jonahmoon]

Move the temporary XTE TE-FL patch behavior into TE-FL native backend implementations. Register KunLunXin layernorm and GEMM operators, route attention backend selection through transformer_engine_klx_torch, and add reference GLU/DGLU fallback implementations.

Description

Please include a brief summary of the changes, relevant motivation and context.

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)
• 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

Changes

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• Change A
• Change B

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

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[lxd-cumt]

LGTM

[zhaoyinglia]

please fix pre-commit format