Add support check mode for all info modules

As it's required by new ansible-test rules.
See https://github.com/ansible-collections/overview/issues/45#issuecomment-893543025
Change-Id: Ib6b73e810b972997b8de2b4a9eb8e07e246823d5

plugins/modules/identity_domain_info.py

@@ -92,7 +92,8 @@ class IdentityDomainInfoModule(OpenStackModule):
     module_kwargs = dict(
         mutually_exclusive=[
             ['name', 'filters'],
-        ]
+        ],
+        supports_check_mode=True
     )
 
     deprecated_names = ('openstack.cloud.identity_domain_facts')