[examples] Update ReduxExample (#4267)

Using two new utils:
1. `createNavigationPropConstructor`, which is now preferred over `createReduxBoundAddListener`.
2. `initializeListeners`, which is necessary to trigger the event listeners with the initial state.

examples/ReduxExample/src/navigators/AppNavigator.js

@@ -2,11 +2,12 @@ import React from 'react';
 import PropTypes from 'prop-types';
 import { connect } from 'react-redux';
 import { StackNavigator } from 'react-navigation';
+import { initializeListeners } from 'react-navigation-redux-helpers';
 
 import LoginScreen from '../components/LoginScreen';
 import MainScreen from '../components/MainScreen';
 import ProfileScreen from '../components/ProfileScreen';
-import { addListener } from '../utils/redux';
+import { navigationPropConstructor } from '../utils/redux';
 
 export const AppNavigator = StackNavigator({
   Login: { screen: LoginScreen },
@@ -20,17 +21,14 @@ class AppWithNavigationState extends React.Component {
     nav: PropTypes.object.isRequired,
   };
 
+  componentDidMount() {
+    initializeListeners('root', this.props.nav);
+  }
+
   render() {
     const { dispatch, nav } = this.props;
-    return (
-      <AppNavigator
-        navigation={{
-          dispatch,
-          state: nav,
-          addListener,
-        }}
-      />
-    );
+    const navigation = navigationPropConstructor(dispatch, nav);
+    return <AppNavigator navigation={navigation} />;
   }
 }
 

examples/ReduxExample/src/utils/redux.js

@@ -1,15 +1,12 @@
 import {
   createReactNavigationReduxMiddleware,
-  createReduxBoundAddListener,
+  createNavigationPropConstructor,
 } from 'react-navigation-redux-helpers';
 
 const middleware = createReactNavigationReduxMiddleware(
-  "root",
-  state => state.nav,
+  'root',
+  state => state.nav
 );
-const addListener = createReduxBoundAddListener("root");
+const navigationPropConstructor = createNavigationPropConstructor('root');
 
-export {
-  middleware,
-  addListener,
-};
+export { middleware, navigationPropConstructor };