Do not use `ssize_t` in `python_arg_parser.[cpp|h]` (#71250)
Summary:
Use `Py_ssize_t` when calling Python API
Use `c10::irange` to automatically infer loop type
Use `size_t` or `unsigned` for unsigned type
Partially addresses https://github.com/pytorch/pytorch/issues/69948
Pull Request resolved: https://github.com/pytorch/pytorch/pull/71250
Reviewed By: atalman
Differential Revision: D33569724
Pulled By: malfet
fbshipit-source-id: c9eb75be9859d586c00db2f824c68840488a2822
