title: Drupal 8: How to get a user field image in template page.html.twig
body: <p>I want to display a users image in a topbar, defined in page.html.twig. 
  The field is called "field_user_image" and is a field of user fields. 
  I've set a default image, whicht should be taken, if the user is not logged in. When the user logs in, I want to pull the image, the user has set as his user image. </p>
  
  <p>Is there any possibility to access the field_user_image in twig, on page.html.twig level? </p>
  
  <p>Thank you very much in advance!</p>