Add the csrf token to window.drf

In the same manner as the current version of base.html from DRF.  This
is part 2 of the removal of base.html.

awx/templates/rest_framework/base.html

@@ -274,7 +274,7 @@
       <script>
         window.drf = {
           csrfHeaderName: "{{ csrf_header_name|default:'X-CSRFToken' }}",
-          csrfCookieName: "{{ csrf_cookie_name|default:'csrftoken' }}"
+          csrfToken: "{% if request %}{{ csrf_token }}{% endif %}"
         };
       </script>
       <script src="{% static "rest_framework/js/jquery-1.12.4.min.js" %}"></script>