Unused RenderingDriver enum

[pochoco24]

Your Godot version: 4.3

Issue description: The OS class has a RenderingDriver enum that is not used anywhere. I'm looking for a get_rendering_driver() method in the docs, but it's either undocumented or not in Godot.

URL to the documentation page: https://docs.godotengine.org/en/stable/classes/class_os.html#enum-os-renderingdriver