Add alias info to torch._C (#84580)
This adds the `AliasInfo` class to torch._C, as defined in https://github.com/pytorch/pytorch/blob/master/torch/csrc/jit/python/init.cpp#L1943. This will fix MYPY errors for missing `Argument` attributes.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/84580
Approved by: https://github.com/lw
