enable mypy check for jit_metaprogramming_utils (#44752)
Summary:
Fixes https://github.com/pytorch/pytorch/issues/42969
enable mypy check for jit_metaprogramming_utils.py and fixed all errors.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/44752
Reviewed By: walterddr
Differential Revision: D23741285
Pulled By: qxu-fb
fbshipit-source-id: 21e36ca5d25c8682fb93b806e416b9e1db76f71e
