Revert "Remove split functional wrapper (#74727)"
This reverts commit a58876ace78df1cfeb136cad592487f34d7e02f1.
Reverted https://github.com/pytorch/pytorch/pull/74727 on behalf of https://github.com/seemethere due to Fails internal use cases, might extend out to external use cases as well. Need to assess overall impact of this change more widely
