Make all doc fragments, module utils, and plugin utils private (#1144)

* Make all doc fragments, module utils, and plugin utils private.

* Remove some unused and no longer needed imports.

This hopefully also fixes the CI issues, which do not happen locally for me...

* Fix formatting.

* Try to make CI happy, again.

* Fix imports.

* Lint.

plugins/modules/docker_image_pull.py

@@ -17,9 +17,9 @@ version_added: 3.6.0
 description:
   - Pulls a Docker image from a registry.
 extends_documentation_fragment:
-  - community.docker.docker.api_documentation
-  - community.docker.attributes
-  - community.docker.attributes.actiongroup_docker
+  - community.docker._docker.api_documentation
+  - community.docker._attributes
+  - community.docker._attributes.actiongroup_docker
 
 attributes:
   check_mode:
@@ -98,16 +98,16 @@ from ansible_collections.community.docker.plugins.module_utils._api.errors impor
 from ansible_collections.community.docker.plugins.module_utils._api.utils.utils import (
     parse_repository_tag,
 )
+from ansible_collections.community.docker.plugins.module_utils._common_api import (
+    AnsibleDockerClient,
+    RequestException,
+)
 from ansible_collections.community.docker.plugins.module_utils._platform import (
     compare_platform_strings,
     compose_platform_string,
     normalize_platform_string,
 )
-from ansible_collections.community.docker.plugins.module_utils.common_api import (
-    AnsibleDockerClient,
-    RequestException,
-)
-from ansible_collections.community.docker.plugins.module_utils.util import (
+from ansible_collections.community.docker.plugins.module_utils._util import (
     DockerBaseClass,
     is_image_name_id,
     is_valid_tag,