fix(cli): allow exclusive arguments as optional

The CLI takes its arguments from the RequiredOptional, which has three fields: required, optional, and exclusive. In practice, the exclusive options are not defined as either required or optional, and would not be allowed in the CLI. This changes that, so that exclusive options are also added to the argument parser.

Closes python-gitlab#2769

gitlab/v4/cli.py

@@ -258,7 +258,7 @@ def _populate_sub_parser_by_class(
                 sub_parser_action.add_argument(
                     f"--{x.replace('_', '-')}", required=True
                 )
-            for x in mgr_cls._create_attrs.optional:
+            for x in mgr_cls._create_attrs.optional + mgr_cls._create_attrs.exclusive:
                 sub_parser_action.add_argument(
                     f"--{x.replace('_', '-')}", required=False
                 )
@@ -274,7 +274,7 @@ def _populate_sub_parser_by_class(
                         f"--{x.replace('_', '-')}", required=True
                     )
 
-            for x in mgr_cls._update_attrs.optional:
+            for x in mgr_cls._update_attrs.optional + mgr_cls._update_attrs.exclusive:
                 if x != cls._id_attr:
                     sub_parser_action.add_argument(
                         f"--{x.replace('_', '-')}", required=False