[ROCm] Enable DeepEP ROCm as all2allbackend for AMD GPUs.

[lcskrishna]

This PR is to integrate changes required to run DeepEP as an all2allbackend on AMD GPUs.

co-authored by : @itej89

The following changes are performed:

• The current codebase is modified to run DeepEP backend OOB on AMD GPUs without any issues.
• FusedBatchedMoE kernels can run on AMD GPUs with float8_e4m3fnuz format added.

Next steps:

• Docker update with ROCm/DeepEP installation steps.
• Unit tests

Purpose

Test Plan

Test Result

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[gemini-code-assist]

Code Review

This pull request enables DeepEP on ROCm for AMD GPUs by adding platform-specific logic, particularly for handling the float8_e4m3fnuz data type and adjusting API arguments. The changes are consistent across the modified files. My main feedback is to refactor a piece of duplicated code in all2all.py to improve maintainability.

[lcskrishna]

cc: @itej89 @amathews-amd