Fix #122769: bpy.utils.register_submodule_factory fails with extensions

The unregister function from register_submodule_factory didn't support
a sub-module name argument.

scripts/modules/bpy/utils/__init__.py

@@ -829,17 +829,16 @@ def register_submodule_factory(module_name, submodule_names):
     def register():
         nonlocal module
         module = __import__(name=module_name, fromlist=submodule_names)
-        submodules[:] = [getattr(module, name) for name in submodule_names]
-        for mod in submodules:
+        submodules[:] = [(getattr(module, mod_name), mod_name) for mod_name in submodule_names]
+        for mod, _mod_name in submodules:
             mod.register()
 
     def unregister():
         from sys import modules
-        for mod in reversed(submodules):
+        for mod, mod_name in reversed(submodules):
             mod.unregister()
-            name = mod.__name__
-            delattr(module, name.partition(".")[2])
-            del modules[name]
+            delattr(module, mod_name)
+            del modules[mod.__name__]
         submodules.clear()
 
     return register, unregister