PR #12031: add gemm autotune log dump
PR #12031: add gemm autotune log dump

Imported from GitHub PR https://github.com/openxla/xla/pull/12031

This PR adds option to dump all gemm fusion autotune results as AutotuningLogs:
- the dump contains all autotune results for all backends including cublas,cudnn, and triton.
- also add fusion name and count (time of occurrence in a given hlo)
Copybara import of the project:

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e65340a856101401e9ee56b4ac258cef9c10c517 by Amir Samani <asamani@nvidia.com>:

add gemm autotune log dump

Merging this change closes #12031

FUTURE_COPYBARA_INTEGRATE_REVIEW=https://github.com/openxla/xla/pull/12031 from Amir-19:gemm_fusion_log e65340a856101401e9ee56b4ac258cef9c10c517
