Examples control panel on mobile takes up the whole screen

[mvaligursky]

See the screenshot. Ideally it would only take as much space as needed by the controls. Perhaps even it should never take more than 50% of the screen and have a scroll bar instead. When displayed, the example could then be resized to the other half, so all of it is visible.

[mvaligursky]

related: https://github.com/playcanvas/engine/issues/5215