Make all doc fragments, module utils, and plugin utils private (#11896)

* Make all doc fragments private.

* Make all plugin utils private.

* Make all module utils private.

* Reformat.

* Changelog fragment.

* Update configs and ignores.

* Adjust unit test names.

plugins/modules/gitlab_runner.py

@@ -34,9 +34,9 @@ requirements:
   - python-gitlab >= 4.0.0 for new runner registration workflow (runner authentication token -
     U(https://docs.gitlab.com/runner/register/#register-with-a-runner-authentication-token))
 extends_documentation_fragment:
-  - community.general.auth_basic
-  - community.general.gitlab
-  - community.general.attributes
+  - community.general._auth_basic
+  - community.general._gitlab
+  - community.general._attributes
 
 attributes:
   check_mode:
@@ -252,13 +252,13 @@ runner:
 from ansible.module_utils.api import basic_auth_argument_spec
 from ansible.module_utils.basic import AnsibleModule
 
-from ansible_collections.community.general.plugins.module_utils.gitlab import (
+from ansible_collections.community.general.plugins.module_utils._gitlab import (
     auth_argument_spec,
     gitlab,
     gitlab_authentication,
     list_all_kwargs,
 )
-from ansible_collections.community.general.plugins.module_utils.version import LooseVersion
+from ansible_collections.community.general.plugins.module_utils._version import LooseVersion
 
 
 class GitLabRunner: