Add support for value listener

Summary:
Adds support for `Animated.Value#addListener` for native driven animated values. Same as #8844 but for iOS. This depends on some JS code in #8844 so only review the 2nd commit and let's wait for #8844 to land first.

**Test plan**
Tested using the UIExplorer example.
Closes https://github.com/facebook/react-native/pull/9194

Differential Revision: D3681749

fbshipit-source-id: 521a61e2221c1ad1f6f40c75dd2dc957361d0271

Examples/UIExplorer/js/NativeAnimationsExample.js

@@ -347,7 +347,6 @@ exports.examples = [
   },
   {
     title: 'Animated value listener',
-    platform: 'android',
     render: function() {
       return (
         <ValueListenerExample />