title: Append Relation Count while using select in eloquent query
body: <p>So i have a query where i want to select specific columns and relation count on a model.</p>
  <p>Something like this</p>
  <pre class="lang-php prettyprint-override"><code>$posts = Post::withCount('comments')-&gt;select('title', 'content')-&gt;get();
  
  foreach ($posts as $post) {
      $post-&gt;comments_count // this is not available because of select in query
  }
  </code></pre>
  <p>Now when I use select in the query <code>comments_count</code> is no longer available. There is <code>$appends</code> option on the model where I can do something like <code>$appends = ['comments_count']</code> on the Post model but it will not work. Any idea how to append the data and use the select on model while querying using eloquent.</p>
  <p>there is <code>$withCount</code> option on the model as well but it will lazy load while querying comments with post (i.e. inverse relation query).</p>