[FX][WIP] Proxyable classes (#56737)
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/56737
Test Plan: Imported from OSS
Reviewed By: Chillee
Differential Revision: D27953073
Pulled By: jamesr66a
fbshipit-source-id: fafc681af7bd5200a9ead2fd0720940913885575
