Back out "Revert D35000703: [WIP][FSDP] Mixed precision enablement" (#75024)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/75024
Original commit changeset: 99295ea4ff02
Original Phabricator Diff: D35000703 (https://github.com/pytorch/pytorch/commit/6b0b088c6caef54d35ad04defe07a4a94831dd27)
ghstack-source-id: 153059190
(Note: this ignores all push blocking failures!)
Test Plan: CI
Reviewed By: pbelevich
Differential Revision: D35287501
fbshipit-source-id: c6c9ada039de27cf9cc477561f92a7f888bdf5f7
(cherry picked from commit a450c7ad75507a8ac637907b51217986d0141dc0)
