carousel: Implement FullScreen and Overlay views

Current index is synchronized between views, with "other" view updating
without animations. Both overlays (native window and in-scene popup)
are self-destructible on close. Animated gifs are auto-playing when
maximizing, and stop playing when current index changes away from them.
Play/Pause button reacts on mouse move, and auto-hides after a brief
timeout.

BUG: 433321 
BUG: 465794 
BUG: 465796 
BUG: 455304 
BUG: 444103