Prevent setRoot from removing existing overlays, added e2e test

e2e/OverlayTest.test.js

     await device.setOrientation('landscape');
     await expect(elementById(testIDs.DIALOG_HEADER)).toBeVisible();
   });
+
+  test('setRoot should not remove overlay', async () => {
+    await elementById(testIDs.PUSH_OPTIONS_BUTTON).tap();
+    await elementById(testIDs.SHOW_OVERLAY_BUTTON).tap();
+    await expect(elementById(testIDs.DIALOG_HEADER)).toBeVisible();
+    await elementById(testIDs.SET_ROOT_BUTTON).tap();
+    await expect(elementById(testIDs.DIALOG_HEADER)).toBeVisible();
+  });
 });

lib/ios/RNNCommandsHandler.m

 	[self assertReady];
 	
 	[_modalManager dismissAllModalsAnimated:NO];
-	[_store removeAllComponents];
 	
 	UIViewController *vc = [_controllerFactory createLayoutAndSaveToStore:layout[@"root"]];
 	
 	UIApplication.sharedApplication.delegate.window.rootViewController = vc;
-	[UIApplication.sharedApplication.delegate.window makeKeyAndVisible];
+	[UIApplication.sharedApplication.delegate.window makeKeyWindow];
 	[_eventEmitter sendOnNavigationCommandCompletion:setRoot params:@{@"layout": layout}];
 	completion();
 }

playground/src/screens/CustomDialog.js

       <View style={styles.root}>
         <Text style={styles.h1} testID={testIDs.DIALOG_HEADER}>Test view</Text>
         <Button title='OK' testID={testIDs.OK_BUTTON} onPress={() => this.onCLickOk()} />
+        <Button title='Set Root' testID={testIDs.SET_ROOT_BUTTON} onPress={() => this.onCLickSetRoot()} />
       </View>
     );
   }
       Alert.alert('Overlay disappeared');
     }
   }
+  
   onCLickOk() {
     Navigation.dismissOverlay(this.props.componentId);
   }
+  
+  onCLickSetRoot() {
+    Navigation.setRoot({
+      root: {
+        component: {
+          name: 'navigation.playground.TextScreen'
+        }
+      }
+    });
+  }
 }
 
 const styles = {

playground/src/testIDs.js

   HIDE_BOTTOM_TABS_ON_PUSH_BUTTON: `HIDE_BOTTOM_TABS_ON_PUSH_BUTTON`,
   SIDE_MENU_LAYOUT_INSIDE_BOTTOM_TAB: `SIDE_MENU_LAYOUT_INSIDE_BOTTOM_TAB`,
   OPEN_SIDE_MENU: `OPEN_SIDE_MENU`,
+  SET_ROOT_BUTTON: `SET_ROOT_BUTTON`,
   
   // Elements
   SCROLLVIEW_ELEMENT: `SCROLLVIEW_ELEMENT`,