Allow TouchControllers to override shouldDisableGestures

Currently only StatusBarTouchController overrides this to always return
false, so that you can swipe down for notifications during transition to
home screen from an app (in gesture nav).

Bug: 137161198
Change-Id: I803c37937d5294810cbe0c1bbffcd5dddcc5ca3b

src/com/android/launcher3/util/TouchController.java

@@ -32,5 +32,9 @@ public interface TouchController {
      */
     boolean onControllerInterceptTouchEvent(MotionEvent ev);
 
+    default boolean allowWhenGesturesDisabled() {
+        return false;
+    }
+
     default void dump(String prefix, PrintWriter writer) { }
 }