Add VR meeting hands-off toggle button to avoid accidental model moves

[Tom Goddard]

It is very easy to accidentally press the grip button on Oculus touch controllers. It would be good to have the equivalent of a "mute" button to disable grip, call it a "hands-off" button. This is only needed in VR meetings where accidental moves are very common. The A or Y button could be assigned to toggle disabling/enabling the grip button (on both controllers). Probably it should also disable the trigger button and thumbstick since the intent is to avoid accidental moves.

This could work by just assigning the buttons to have no operation and remembering the previous assignments to restore them later.

For Vive controllers only the trigger button is a problem (grip is hard to accidentally press) so this toggle could just disable trigger on vive controllers. Could assign one grip button to that toggle.