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_info.py

@@ -22,11 +22,11 @@ description:
 notes:
   - This module was called C(docker_image_facts) before Ansible 2.8. The usage did not change.
 extends_documentation_fragment:
-  - community.docker.docker.api_documentation
-  - community.docker.attributes
-  - community.docker.attributes.actiongroup_docker
-  - community.docker.attributes.info_module
-  - community.docker.attributes.idempotent_not_modify_state
+  - community.docker._docker.api_documentation
+  - community.docker._attributes
+  - community.docker._attributes.actiongroup_docker
+  - community.docker._attributes.info_module
+  - community.docker._attributes.idempotent_not_modify_state
 
 options:
   name:
@@ -144,11 +144,11 @@ 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 (
+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,
 )