[pytorch] tweak code analyzer script to handle new namespaces (#40276)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/40276
- add a couple new namespaces;
- handle the case where both contextual namespace and opreator namespace
are set (BackendSelectRegister.cpp and #39401);
- improve error message;
Test Plan: Imported from OSS
Differential Revision: D22135686
Pulled By: ljk53
fbshipit-source-id: 14d359c93573349b8fe1e05d7e44d875295a5f6d
