Add auto-scroll/scroll in place functionality

[EzraMoore65]

Would like to be able to have the parallax background scroll without moving the camera. I imagine it could be done in a fashion similar to Godot's parallax background where it can be moved either in correspondence with the camera, or using a layer offset property which is independent from the camera. An auto-scroll feature would also fit nicely with this, but that part is more of a luxury.