Create torch.distributed.shard package. (#71742)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/71742
We have many sharding components currently:
torch.distributed._sharded_tensor, torch.distributed._sharding_spec,
torch.distributed._sharded_optimizer and more coming.
As a result, organizing all of this under the `torch.distributed.shard`
package. For BC reasons, I'm still keeping the old packages and have them just
reference the new package.
ghstack-source-id: 147899768
Test Plan: waitforbuildbot
Reviewed By: fduwjj, wanchaol
Differential Revision: D33755913
fbshipit-source-id: dc692b31e2607063d55dfcb3db33ec53961d5a5b
(cherry picked from commit 5b6885f3587786217f8ce143f2329ceec618404e)
