Minor tweaks to rpc message api (#28326)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/28326
- Message::type() should return a MessageType, not const MessageType&,
since MessageType is just an enum.
- Add moveTensors() method for parallelism with movePayload().
ghstack-source-id: 92236443
Test Plan: buck test mode/dev-nosan caffe2/test/...
Differential Revision: D18021692
fbshipit-source-id: 5b2f5806f104a221de8df0282f3e395d15e5bfe4
