Allow RPC framework to use rank in addition to WorkerInfo and name. (#46221)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/46221
The RPC framework only allowed sending RPCs based on provided
WorkerInfo or name. When using RPC with DDP, sometimes it might just be easier
to refer to everything in terms of ranks since DDP doesn't support names yet.
As a result, support a `to` parameter in the RPC APIs which allow for
specifying a rank as well would be helpful.
ghstack-source-id: 114207172
Test Plan:
1) waitforbuildbot
2) Unit Tests
Reviewed By: mrshenli
Differential Revision: D24264989
fbshipit-source-id: 5edf5d92e2bd2f213471dfe7c74eebfa9efc9f70
