Improve input controller UI/UX in VR

[takahirox]

I added the input controller prototype in VR mode. User can push a button if XR input device touches a button of a big controller.

I realized this approach has some problems. First, fine user control is hard. Second, it doesn't work for 3dof controllers.

An solution idea from Kevin is mapping device controller buttons to NES input controller buttons, for example touchpad axes to cursor, trigger and touchpad press to A/B buttons.

https://www.w3.org/TR/webxr-gamepads-module-1/#xr-standard-gamepad-mapping