Implement the patterns module for the multi subgraph rewriter. (#71181)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/71181
This diff introduces the patterns module that defines a pattern-replacement pair for the experimental multi subgraph rewriter.
Test Plan: Tested locally. Unit test suite forthcoming.
Reviewed By: ajauhri
Differential Revision: D32374542
fbshipit-source-id: 4ae8da575976e96b02c5c33c6ae2a0943fc7f126
