Unstash hotseat immediately if go out of the launcher home.

When navigation mode is set to 3 buttons, it is possible for user to
click on recent apps button, so for such scenario taskbar should be
immediately un-stashed

Test: Manual
Set 3 buttons navigation mode. Go to Launcher home. Expand bubble bar.
Press recent apps button. Press the home button. Observe hotseat is
visible. Video:
http://recall/-/gx8ASgewUeUS3QYohfrd1J/fX0gSp18Riw8mYYAw0wj8W

Bug: 367488218
Flag: com.android.wm.shell.enable_bubble_bar
Change-Id: Id65fd9add720125a340294311d470f2be50d43f8

quickstep/src/com/android/launcher3/taskbar/TaskbarStashController.java

@@ -402,6 +402,11 @@ public class TaskbarStashController implements TaskbarControllers.LoggableTaskba
         mControllers.uiController.stashHotseat(stash);
     }
 
+    /** Instantly un-stashes the hotseat. */
+    public void unStashHotseatInstantly() {
+        mControllers.uiController.unStashHotseatInstantly();
+    }
+
     /**
      * Returns whether the taskbar should be stashed in apps (e.g. user long pressed to stash).
      */