This pr adds ConvertGather7ToGather1 pass to frontend before MergeGatherGatherElements pass, to make it so that when MergeGatherGatherElements is ran, any v7::Gather will be replaced with v1::Gather
This pr adds ConvertGather7ToGather1 pass to frontend before MergeGatherGatherElements pass, to make it so that when MergeGatherGatherElements is ran, any v7::Gather will be replaced with v1::Gather