Initial commit of taskbar stashing

- Added StashedHandleViewController to provide properties such as ViewOutlineProvider to animate the handle that's shown in place of taskbar while it's stashed
- Added TaskbarStashController to coordinate the stashed state, including orchestrating the animation across taskbar controllers
- Added TaskbarStashInput consumer to detect long press in the nav region when taskbar is stashed

Behavior:
- Long pressing taskbar background animates to the stashed state by morphing the TaskbarView into the stashed handle view and offsetting the background offscreen
- We persist the stashed state across app launches and reboot; to unstash, long press the stashed handle
- We also visually unstash when going back home

Test: long press tasbkar background when in an app to stash it, long press the resulting stashed handle to unstash; while stashed, swipe up to home to also unstash until launching another app
Bug: 189503603
Change-Id: I698eff785388dff1ef717c76879719d6af236c2d

quickstep/src/com/android/quickstep/RecentsAnimationController.java

@@ -46,6 +46,8 @@ public class RecentsAnimationController {
     private boolean mUseLauncherSysBarFlags = false;
     private boolean mSplitScreenMinimized = false;
     private boolean mFinishRequested = false;
+    // Only valid when mFinishRequested == true.
+    private boolean mFinishTargetIsLauncher;
     private RunnableList mPendingFinishCallbacks = new RunnableList();
 
     public RecentsAnimationController(RecentsAnimationControllerCompat controller,
@@ -145,6 +147,7 @@ public class RecentsAnimationController {
 
         // Finish not yet requested
         mFinishRequested = true;
+        mFinishTargetIsLauncher = toRecents;
         mOnFinishedListener.accept(this);
         mPendingFinishCallbacks.add(callback);
         UI_HELPER_EXECUTOR.execute(() -> {
@@ -201,4 +204,12 @@ public class RecentsAnimationController {
     public RecentsAnimationControllerCompat getController() {
         return mController;
     }
+
+    /**
+     * RecentsAnimationListeners can check this in onRecentsAnimationFinished() to determine whether
+     * the animation was finished to launcher vs an app.
+     */
+    public boolean getFinishTargetIsLauncher() {
+        return mFinishTargetIsLauncher;
+    }
 }