This commit provides a few fixes for the non-fullscreen view:

  * remove the subquiz link on slides of type 'quiz' in the sidebar;
  * hide completion icons in sidebar if not member;
  * only show the 'embed on your website' option when a slide has an embed
    code. This will prevent slides of type 'certification' or 'quiz' to
    display an empty embed box;

Commit linked to task ID 1941250 and PR #31977