[WIP][FX] Add Interpreter and Transformer (#50420)
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/50420
Test Plan: Imported from OSS
Reviewed By: zdevito
Differential Revision: D25880330
Pulled By: jamesr66a
fbshipit-source-id: 27d34888e36e39924821fed891d79f969237a104
