PR #13062: FP8 Windowed Einsums
PR #13062: FP8 Windowed Einsums

Imported from GitHub PR https://github.com/openxla/xla/pull/13062

Extends the windowed einsum handler to support collective FP8 GEMMs by shifting the dequantization of dot operands into the body of the while loops of all-gather and reduce-scatter windowed einsums.
Copybara import of the project:

--
3ea415d65e47087bb077fa2b13e34c82a4dae87b by Philipp Hack <phack@nvidia.com>:

Shifts the the dequantization of FP8 operands into the while body of windowed einsums.


Merging this change closes #13062

Reverts changelist 641225077

FUTURE_COPYBARA_INTEGRATE_REVIEW=https://github.com/openxla/xla/pull/13062 from philipphack:u_fp8_windowed_einsum_xla 3ea415d65e47087bb077fa2b13e34c82a4dae87b
