Migrate arc-vr-ui completely to the new InputSystem

[Helliaca]

All of arc-vr currently only uses the new InputSystem, except for arc-vr-ui, which partially still relies on the old one.

The VRInput component only works when placed alongside a 'StandaloneInputModule', a 'InputSystemUIModule' will make the VRInput component obsolete, and thus lead to following issues:

• The key-bindings set on the UIInteractionProvider will not have any effect whatsoever. The inputs will instead be taken from the action-list set on the InputSystemUIModule.
• The inputs from the other controller will be used by UIInteractionProvider as well. (Eg. you can point to a UI element with the left controller, then press the trigger on the right controller to click, even when the right controller has no components attatched.