Update attention example attention.ipynb

[anhminhnguyenhoang]

Description

Create the ROCm version of the example notebook attention.ipynb.

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 refractor

Changes

Please list the changes introduced in this PR:

• Created a jupyter notebook named attention-rocm.ipynb with details on ROCm backend from the original notebook attention.ipynb for cuDNN
• Added some modifications for local import of the module tests.pytorch.fused_attn.test_fused_attn
• attention-rocm.ipynb contains a hacky fix to be adviced on how to resolve for being unable to import the function transformer_engine.pytorch.attention._flash_attn_3_is_installed on Docker image rocm/megatron-lm:v25.3

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