GH-116380: Move pathlib globbing implementation into `pathlib._glob` (#118562)

Moving this code under the `pathlib` package makes it quite a lot easier
to backport in the `pathlib-abc` PyPI package. It was a bit foolish of me
to add it to `glob` in the first place.

Also add `translate()` to `__all__` in `glob`. This function is new in
3.13, so there's no NEWS needed.