Summary:
Curently FlatList does not implement setting native props directly like the old ListView did. This pr introduce the `setNativeProps` function which delegates to MetroListView or VirtualizedList. Thos don't have `setNativeProps` handling either, so, I delegated further to the respective ListView and Scroll components, which do have handling for it, thus, allowing to set the native props through FlatList.

Create a project with a FlatList and change a native property using `setNativeProps`:

```javascript
  componentDidMount() {
        setInterval(() => {
            this.list.setNativeProps({ style: {backgroundColor:"white"} })
        }, 1000)
    }

  render() {
    return (
      <View style={styles.container}>
        <FlatList ref={component => this.list = component}
                  style={{backgroundColor:"black"}}
                  data={[{key: 'a'}, {key: 'b'}]}
                  renderItem={({item}) => <Text>{item.key}</Text>} />
      </View>
    )
  }
```

Fixes facebook#13501
Closes facebook#13529

Differential Revision: D5283593

Pulled By: sahrens

fbshipit-source-id: 8f96f88e286042d82452fef924689b5a8a783987