Fix controller navigation on two panel launcher home

Test: manual test with a game controller, check on both normal and two panel home
Bug: 187205980
Change-Id: I2515e476556098acf407c0bdcd634e3dd1cb308c

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

@@ -36,6 +36,15 @@ public class IntSet implements Iterable<Integer> {
         }
     }
 
+    /**
+     * Appends the specified IntSet's values to the set if they does not exist, then returns the
+     * original set that now also contains the new values.
+     */
+    public IntSet addAll(IntSet other) {
+        other.forEach(this::add);
+        return this;
+    }
+
     /**
      * Removes the specified value from the set if it exist.
      */