title: Make Django admin ManyToMany field filter_horizontal searchable on both sides?
body: <p>Is there a way to make a ManyToMany field that uses filter_horizontal text searchable from both sides. By default the left side is searchable but the right is not.</p>
  
  <p><img src="https://i.stack.imgur.com/UXNNr.png" alt="enter image description here"></p>