gh-106531: Remove importlib.resources._legacy

[jaraco]

Syncs with importlib_resources 6.0.

• Issue: Refresh importlib.resources #106531

[jaraco]

I'm going to proceed with the merge to give as much visibility to the change as possible, but happy to revisit if needed.

[CAM-Gerlach]

I realize this is somewhat late to the party, but is there any chance we can revert this for one release, so tools like pre-commit don't have to drop compatibility with Python 3.8 prior to it being EOL to support Python 3.13 before release (see, e.g., pre-commit/pre-commit#3042 , or else have to include a bunch of kludgy compatibility code for one Python release as in mesonbuild/meson#11998 .

[jaraco]

I realize this is somewhat late to the party, but is there any chance we can revert this for one release, so tools like pre-commit don't have to drop compatibility with Python 3.8 prior to it being EOL to support Python 3.13 before release (see, e.g., pre-commit/pre-commit#3042 , or else have to include a bunch of kludgy compatibility code for one Python release as in mesonbuild/meson#11998 .

Sorry I missed this message earlier. It's been a rough winter season for me. Huge thanks to encukou for addressing this request in #116608.