Remap net name inside arg.n for AsyncIf operator
Summary: Similar to If operator, AsyncIf also contains nets in args. It needs the same handling.
Test Plan:
New unit test test_control_op_remap
`buck test caffe2/caffe2/python:core_test`
Also it worked end to end in prototype of dist bulk eval workflow f226680903
Reviewed By: yyetim
Differential Revision: D24451775
fbshipit-source-id: 50594e2ab9bb457329ed8da7b035f7409461b5f6
