[Reland][FSDP] Implement apply() (#72925)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/72925
Reland with fix to add the owner string in test file
ghstack-source-id: 149280348
Test Plan: CI
Reviewed By: zhaojuanmao
Differential Revision: D34273858
fbshipit-source-id: 2174c1d71fcc5148282d94e375071a50b92114f2
(cherry picked from commit 158762bbb36f9652d93b3f23beca51c319435cc7)
