[GPU] Enable optimize_for_metal in fbcode (#47102)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/47102
Since the current mobile end to end workflow involves using `optmize_for_mobile` in python, the goal here is to be able to use `optmize_for_mobile(m, backend="metal")` in fbcode.
ghstack-source-id: 115749752
Test Plan:
1. Be able to export models for metal (see the next diff)
2. Make sure the change won't break the OSS workflow
3. Make sure the change won't break on the mobile bulild.
Reviewed By: xcheng16
Differential Revision: D24644422
fbshipit-source-id: bd77e22f0799533a96d048207932055fd051a67e
