Invoke onSuccess for initial pushed child

lib/android/app/src/main/java/com/reactnativenavigation/viewcontrollers/StackController.java

                 getView().removeView(toRemove.getView());
                 listener.onSuccess(child.getId());
             }
+        } else {
+            listener.onSuccess(child.getId());
         }
     }
 

lib/android/app/src/test/java/com/reactnativenavigation/viewcontrollers/StackControllerTest.java

     @Test
     public void push() {
         assertThat(uut.isEmpty()).isTrue();
-        uut.push(child1, new CommandListenerAdapter());
+        CommandListenerAdapter listener = spy(new CommandListenerAdapter());
+        uut.push(child1, listener);
         assertContainsOnlyId(child1.getId());
+        verify(listener, times(1)).onSuccess(child1.getId());
     }
 
     @Test