[torchgen] Add logic in annotation parser to accept alias set (#83501)
Extending the current regex in `model.py` to support annotation alias set. See issue #83214.
Ideally we should have a full fledged lexer similar to `schema_type_parser.cpp`, since regex can be more and more difficult to read if we add more support to it.
Adding this to unblock this issue for now.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/83501
Approved by: https://github.com/SherlockNoMad
