Add RunOperator for using FunctionSchema registered ops easily in caffe2 (#16173)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/16173
Helper to make it easy to run ops in caffe2
Reviewed By: smessmer
Differential Revision: D13468240
fbshipit-source-id: 2276c7870af6dcdf829957f005fd16ac1ef319b5
