Separate Inventory Source API vs RBAC testing

Introduced new decorator for patching an access method,
does legwork of inserting into access registry so that
tests that test the API can mock RBAC behavior.

awx/main/access.py

@@ -95,7 +95,7 @@ def check_user_access(user, model_class, action, *args, **kwargs):
             continue
         result = access_method(*args, **kwargs)
         logger.debug('%s.%s %r returned %r', access_instance.__class__.__name__,
-                     access_method.__name__, args, result)
+                     getattr(access_method, '__name__', 'unknown'), args, result)
         if result:
             return result
     return False