title: easyadmin entity field's dynamic custom choices
body: <p>Installed easyadminbundle with symfony 4, configured for an entity name <code>Delivery</code> and it has a field associated to another entity name <code>WeeklyMenu</code>:</p>
  
  <p>easy_amin.yaml:</p>
  
  <pre><code>Delivery:
  ...
        form:
          fields:
            - { property: 'delivered'}
            - { property: 'weeklyMenu', type: 'choice', type_options: { choices: null }}
  </code></pre>
  
  <p>I need a <strong>dynamically filtered results</strong> of <code>weeklyMenu</code> entity here, so I can get a list of the next days menus and so on. It's set to <code>null</code> now but have to get a filtered result here.</p>
  
  <p>I've read about overriding the <code>AdminController</code> which I stucked with it. I believe that I have to override easyadmin's query builder that listing an associated entity's result.</p>