[PT-D][FSDP] Implement _clip_grad_norm_ for FSDP (#73405)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/73405
Implement the `_clip_grad_norm_` for FSDP, issue: https://github.com/pytorch/pytorch/issues/72548
ghstack-source-id: 151059433
Test Plan: CI
Reviewed By: rohan-varma
Differential Revision: D34230605
fbshipit-source-id: bbac7a6e49276e0f0502e2f4466c984aee2629fa
(cherry picked from commit f10d090cd11489608ab3f67f52e3e950cd9f7dea)
