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: D18012804
Pulled By: bwasti
fbshipit-source-id: 9b6acdeb0656d2d7911b0ed63f4d47ecca5473b9
