[pytorch] add script to run all codegen (#46243)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/46243
Add util script to test whether any codegen output changes.
Test Plan: Imported from OSS
Reviewed By: ezyang
Differential Revision: D24388873
Pulled By: ljk53
fbshipit-source-id: ef9ef7fe6067df1e0c53aba725fc13b0dfd7f4c2
