Re-land: [XLA:GPU] Store fusion_roots and fusion_heroes as HloInstructionAdaptor in HloFusionAnalysis.
Re-land: [XLA:GPU] Store fusion_roots and fusion_heroes as HloInstructionAdaptor in HloFusionAnalysis.

Reverts 23ac61b9f8a787925a089772a70e288fe42a336c
