Expose sliding window attn to TE-JAX API

[huanghua1994]

Description

Recent models employ sliding window attention (SWA). Some frameworks use cuDNN fused attention through the TE-JAX Flash Attention API. The SWA support has not been exposed to this API yet. However, on the backend TE does have support for the SWA. This PR expose the SWA support to the Flash Attention API.

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

Please list the changes introduced in this PR:

Expose sliding window attention to the TE-JAX API

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

[mgoldfarb-nvidia]

Thank you for this PR! Have a few small questions/comments.

[mingxu1067]

Could you port the SWA to flax and praxis modules as well?

[mgoldfarb-nvidia]

LGTM! Please address @mingxu1067 comments and will be in good shape.