Pass existing object references within access methods

This avoids re-loading objects from the database in our
chain of permission checking, wherever possible.
access.py is equiped to handle object references instead
of pk ints, and permissions.py is changed to pass those refs.

awx/api/renderers.py

@@ -48,7 +48,8 @@ class BrowsableAPIRenderer(renderers.BrowsableAPIRenderer):
         obj = getattr(view, 'object', None)
         if obj is None and hasattr(view, 'get_object') and hasattr(view, 'retrieve'):
             try:
-                obj = view.get_object()
+                view.object = view.get_object()
+                obj = view.object
             except Exception:
                 obj = None
         with override_method(view, request, method) as request: