docker_container: fix check mode for container creation (#42380)

* Create copy of HostConfig object before adding it to results.

* Create general sanitize function in docker_common. Using it for all return values of docker_container.

* Make Python 2.6 compatible.

lib/ansible/module_utils/docker_common.py

@@ -120,6 +120,24 @@ if not HAS_DOCKER_PY:
         pass
 
 
+def sanitize_result(data):
+    """Sanitize data object for return to Ansible.
+
+    When the data object contains types such as docker.types.containers.HostConfig,
+    Ansible will fail when these are returned via exit_json or fail_json.
+    HostConfig is derived from dict, but its constructor requires additional
+    arguments. This function sanitizes data structures by recursively converting
+    everything derived from dict to dict and everything derived from list (and tuple)
+    to a list.
+    """
+    if isinstance(data, dict):
+        return dict((k, sanitize_result(v)) for k, v in data.items())
+    elif isinstance(data, (list, tuple)):
+        return [sanitize_result(v) for v in data]
+    else:
+        return data
+
+
 class DockerBaseClass(object):
 
     def __init__(self):