Call aten ops through c10 dispatcher (#23668)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/23668
- The eager mode frontend now calls operators who are defined in native_functions.yaml with `use_c10_dispatcher: True` through the c10 dispatcher and not anymore through globalATenDispatch().
- These operators aren't registered with globalAtenDispatch anymore, only on c10 now.
- Backend extensions calling globalATenDispatch().registerOp() to add their own kernels still work, this function will forward the registration to the c10 dispatcher for them.
ghstack-source-id: 90130455
Test Plan: benchmarks at https://docs.google.com/document/d/1gpzKZcFf1JJameY1vKxF7Cloul9s6D8HKIK2_Pp1hFo/edit#
Differential Revision: D16603133
fbshipit-source-id: 991f17b355e9c78c5e86fee4fa381df7ab98ac82
