title: add array key value as an key/value within array of object
body: <pre><code>Array
  (
  
      [0] =&gt; [{"type":"textarea","label":"Text Area","className":"form-control","name":"textarea-1519387047895","subtype":"textarea"},{"type":"text","label":"Text Field","className":"form-control","name":"text-1519387470117","subtype":"text"}]
  
      [1] =&gt; [{"type":"text","label":"Text Field","className":"form-control","name":"text-1519387050946","subtype":"text"}]
  
  )
  </code></pre>
  
  <p>I want to add value like this</p>
  
  <pre><code>Array
  (
  
      [0] =&gt; [{"type":"textarea","label":"Text Area","className":"form-control","name":"textarea-1519387047895","subtype":"textarea","arraykey":"0"},{"type":"text","label":"Text Field","className":"form-control","name":"text-1519387470117","subtype":"text","arraykey":"0"}]
  
      [1] =&gt; [{"type":"text","label":"Text Field","className":"form-control","name":"text-1519387050946","subtype":"text","arraykey":"1"}]
  
  )
  </code></pre>