title: FlatList numColumns and flex justifyContent issue
body: <p>I have a flat list where I would like to display in a grid like fashion using up 100% width of the container however I cannot seem to achieve this with flatlist.<br>
  Space-between as I have goes to the sides (as per image) space-around centres the boxes in the container, space evenly does the same, flex-start with a marginRight is not accurate. Not entirely sure how to achieve this? Thanks</p>
  
  <pre><code>&lt;FlatList
      numColumns={3}
      columnWrapperStyle={{ justifyContent: "space-between"}}
      contentContainerStyle={{
         marginTop:20 
      }}
      data={data}
      keyExtractor={item =&gt; item.id}
      renderItem={renderItemComponent}
  /&gt;
  </code></pre>
  
  <p><strong>Issue:</strong> 
  Needing like space-between fashion but if theres 2 items in the row, then move second item to middle based on dynamic data?</p>
  
  <p><a href="https://i.stack.imgur.com/RrtPW.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/RrtPW.png" alt="enter image description here"></a></p>