[package] mangle imported module names (#50049)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/50049
Rationale and implementation immortalized in a big comment in
`torch/package/mangling.md`.
This change also allows imported modules to be TorchScripted
Test Plan: Imported from OSS
Reviewed By: pbelevich
Differential Revision: D25758625
Pulled By: suo
fbshipit-source-id: 77a99dd2024c76716cfa6e59c3855ed590efda8b
