title: Autofocus on input elements inside a tab-group
body: <p>Is there a way to set autofocus on an input elements inside a mat-tab elements inside of a mat-tab-group? 
  Current behaviour is that focus is set to the first tab's label.</p>
  
  <p>I tried writing a directive that sets a deferred focus on the element, but that only works if the timeout is high enough > 500ms, hoever this doesn't seem like a good choice.</p>
  
  <p>Is there a way to prevent the mat-tab-groups from grabbing the focus? I believe this has something to do with accessability but in my case it's just very unhelpful.</p>