Add a screen to toggle onscreen touch control visibility.

This screen will allow the user to toggle every single onscreen touch control's visibility except for platforms that support the pause/menu button: that's the only button that cannot be disabled(for safety reasons).

It has one quirk that I'm unsure of how to solve:
1. Choices with images centered the image, but Choices with text cannot be centered apparently.

Other than that it seems to work fine, and can even be toggled in-game.