[DDP Comm Hook] Create a noop hook for performance debugging (#64344)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/64344
As title.
Additionally, avoid using numpy array in test_ddp_hooks.py.
ghstack-source-id: 137170449
Test Plan: buck test mode/dev-nosan caffe2/test/distributed/algorithms/ddp_comm_hooks:test_ddp_hooks -- test_ddp_comm_hook_noop_hook
Reviewed By: rohan-varma
Differential Revision: D30693220
fbshipit-source-id: e17f0d1c6198863cf20a53566f586a6bff602522
