Add a wrapper to wrap all optimization for mobile. (#35227)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/35227
This wraps.
1. Conv BN folding (not mobile specific)
2. insert XNNPACK conv2d/Linear ops
3. Remove prepacking ops.
Test Plan: Imported from OSS
Differential Revision: D20603562
fbshipit-source-id: ff373af7112c070ec6198bac51845282e09ff1f8
