[FX] Shape propagation example (#45589)
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/45589
Test Plan: Imported from OSS
Reviewed By: zdevito
Differential Revision: D24024606
Pulled By: jamesr66a
fbshipit-source-id: 5340eab20f805c232bfeb37e4e2156f39a161c19
