Fix bubble relaunch by deferring TaskView animation.

When launching a recycled task into a TaskView that lacks a surface,
such as reopening a collapsed bubble via a trampoline activity in
desktop mode, the transition could be initiated before the TaskView was
ready. TaskViewTransitions would handle the animation by hiding the
task.

This change introduces a readiness check to ensure that all TaskViews
involved in a transition are prepared for animation. A TaskView is
considered not ready if its surface has been destroyed. If any TaskView
is not ready, TaskViewTransitions now returns false from
startAnimation(), deferring the transition to another handler. It allows
LaunchNewTaskBubbleForExistingTransition in DefaultMixedHandler to
correctly process the transition, ensuring the bubble reopens as
expected.

Bug: 432606505
Flag: EXEMPT BUGFIX
Test: atest WMShellUnitTests:TaskViewTest
Test: atest WMShellUnitTests:TaskViewTransitionStartAnimationTest
Test: atest WMShellUnitTests:BubbleTransitionsTest
Change-Id: Ia1d71b6f55bd1fd7f80a72dd9b34702e10cedd24