Add support for fusion-start and fusion-done operations in HLO.
Add support for fusion-start and fusion-done operations in HLO.

FUTURE_COPYBARA_INTEGRATE_REVIEW=https://github.com/tensorflow/tensorflow/pull/65936 from tensorflow:Surya-GatherV2_axis_fix d7a541ea2d67543660bb1c14255afb6c1b999b08
