title: Loopback Model - add a count field for a hasMany relation Model
body: <p>Is there a way to count the number of instance of a related model, without using an <code>include</code> on the filter?</p>
  
  <p>I already found <a href="https://www.npmjs.com/package/loopback-counts-mixin" rel="noreferrer">loopback-counts-mixin</a>, but I am hoping that there is a native way of doing it.</p>