* gh-95218: Move tests for importlib.resources into test_importlib.resources.
* Also update makefile
* Include test_importlib/resources in code ownership rule.
* Unify behavior in ResourceReaderDefaultsTests and align with the behavior found in importlib_resources.
* Equip NamespaceLoader with a NamespaceReader.
* Apply changes from importlib_resources 5.0.4