Address a couple small followups for TaskbarInsetsController

- Added no-op onDestroy()
- Reformated some if conditions, also adding
  AbstractFloatingView.hasOpenView()

Test: TaplTestsTaskbar
Bug: 215411414
Change-Id: I89b39ca5fabd03f5ac0f25d6ef69170683cf060d

src/com/android/launcher3/AbstractFloatingView.java

@@ -207,6 +207,13 @@ public abstract class AbstractFloatingView extends LinearLayout implements Touch
         return getView(activity, type, true /* mustBeOpen */);
     }
 
+    /**
+     * Returns whether there is at least one view of the given type where {@link #isOpen()} == true.
+     */
+    public static boolean hasOpenView(ActivityContext activity, @FloatingViewType int type) {
+        return getOpenView(activity, type) != null;
+    }
+
     /**
      * Returns a view matching FloatingViewType, and {@link #isOpen()} may be false (if animating
      * closed).