Use FunctionSchema instead of char* for dispatch (#28295)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/28295
Previous PR was landed in a broken state
Test Plan: Imported from OSS
Differential Revision: D18066217
Pulled By: bwasti
fbshipit-source-id: 665de7b28145885d6b01f5f212897ac3f8f6270f
