Region mover set_uid

[TokisanGames]

Last time I ran region_mover.gd in 4.5.1 it caused a bunch of duplicate UID errors.

WARNING: UID duplicate detected between res://scenes/terrains/world/terrain3d_04-06.res and res://scenes/terrains/world/terrain3d_03-07.res.
     at: _process_file_system (editor/file_system/editor_file_system.cpp:1377)

The task is to force a new uid after renaming files. It looks like after the final rename we can do something like:

	if ResourceLoader.get_resource_uid(path) == ResourceUID.INVALID_ID:
		ResourceSaver.set_uid(path, ResourceUID.create_id())

See:

• How to manually fix it: No fix is offered for existing duplicate UIDs godotengine/godot#102490 (comment)
• Expose ResourceSaver.set_uid() to scripting. godotengine/godot-proposals#11971
• Expose set_uid() godotengine/godot#87714
• Make script UIDs optional godotengine/godot#87706 (comment)
• Expose scene unique id functionality in Resource godotengine/godot#88111