torch.inference_mode: add type hints (#94223)
Copied the type hints from the other context managers.
Not sure how to add type hints for `clone` since it returns the same class. The `Self` type isn't introduced until Python 3.11 and mypy just recently added support for it. Could also use `"inference_mode"` with quotes to avoid using it before it's declared, or `from __future__ import annotations` to allow its use without quotes. Or we could just skip it.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/94223
Approved by: https://github.com/albanD
