System Bars animation for fixed rotation transform

Fade out system bars when the fixed transform is starting and fade
them in once its finished.

In other words, if mFixedRotationLaunchingApp is set, the hide
(fade out) animation will start. And if mFixedRotationLaunchingApp
is cleared or seamless rotation is done for fixed rotation, the
show (fade in) animation will start.

Note a special case: the fixed rotation app hides the system bars,
so there may be no window to rotate. Then the show animation will
apply immediately (though they are invisible) to make sure the bars
can be visible by transient state.

Bug: 150676212
Bug: 156864004
Test: Manual: open and close a landscape application, and open and
      immediately cancel opening animation.
      Manual: open a landscape application which hides status bar
      and navigation bar. The bars should still be visible after
      swiping from edge of screen.
Test: WmTests:DisplayContentTests#testApplyTopFixedRotationTransform

Change-Id: Ic326b4bda44b39c875aeb27f33fba31a5cfcfc66