title: Multiline TextInput placeholder not center aligned
body: <p>The placeholder is not positioned at the center, when 'multiline' is set to true. How to place the placeholder at the center and also make sure the cursor starts before the placeholder text(similar to the placeholder text in a non-multiline TextInput)? I would like to have the TextInput to be of width 100%.</p>
  
  <pre><code>class Something extends Component {
  render() {
   return (
    &lt;View style={{paddingTop: 20}}&gt;
     &lt;TextInput placeholder="Single-Line" style={styles.input}/&gt;
     &lt;TextInput placeholder="Multi-line" style={[styles.input,{backgroundColor: 'pink'}]} multiline={true}/&gt;
    &lt;/View&gt;
   )
  }
  }
  
  const styles = StyleSheet.create({
   input: {
   height: 30,
   textAlign: 'center',
   backgroundColor: 'red'
  }
  });
  </code></pre>
  
  <p><a href="https://i.stack.imgur.com/2Lxo6.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/2Lxo6.png" alt="enter image description here"></a>
  <a href="https://i.stack.imgur.com/7yZKi.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/7yZKi.png" alt="enter image description here"></a></p>