Correct the pair-to-pair transition animation

...by cache live tile tasks while enter recents.

For normal pair-to-pair switch, evict live tile tasks in finish
transaction, so the task won't suddely become fullscreen task, which
break the recents animation. This also fix an issue that previous task
will occluding the live tile task after doing pair-to-pair switch, which
was because there didn't evict task after start new task, and the
pending enter transition was consumed in StageCoordinator.

For mixed transition case(pair-to-pair + display change), the live tile
tasks will be evict when process pending enter animation.

Bug: 275349333
Bug: 280742823
Test: atest SwitchBetweenSplitPairs
Test: atest SplitTransitionTests
Test: atest TaplTestsTaskbar
Test: compose a split pair then enter recents, cancel recents, verify
nothing change.
Test: Compose 2 split pair, do pair-to-pair switch several times,
verify both pair won't be dismissed as standalone task in recents.
Test: compose 2 split pair, enter recents, rotate device, do
pair-to-pair switch, verify the result after mixed animation is
correct, and each pair won't be dismissed.

Change-Id: Iea415a29a8ed9573c7852a9f42b1c07fbe120df9