Some random issues I've noticed while looking at QSGAnimationDriver. Noted here so we don't lose them.

• Always uses QGuiApplication::primaryScreen(), but animation rates should be tied to the screen the given window is on
• Doesn't handle QScreen::refreshRateChanged()
• Uses manual timer-based animation driver based on refresh rate of screen
  • Ideally we should drive animations from sources like CADisplayLink on macOS
    • Which would make sense as a generic animation driver in QtGui