title: Call a method when ng-template is visible
body: <p>Does ng-template have any events when it is visible or active in the scope
  <strong>or</strong> is it possible to execute any method in such way to call it from the container?</p>
  
  <pre><code>&lt;ng-template (active/vissible)="callMethod()"&gt; ... &lt;/ng-template&gt;
  </code></pre>
  
  <p>(Or)</p>
  
  <pre><code>&lt;ng-container *ngTemplateOutlet="mytemplate" &gt;&lt;/ng-container&gt;
  </code></pre>