Fix netconf plugin set_option (#43589)

* To enable set config option with `Netconf` plugin
  inherit `NetconfBase` class from `AnsiblePlugin` parent class

lib/ansible/plugins/netconf/__init__.py

@@ -19,12 +19,12 @@
 from __future__ import (absolute_import, division, print_function)
 __metaclass__ = type
 
-from abc import ABCMeta, abstractmethod
+from abc import abstractmethod
 from functools import wraps
 
 from ansible.errors import AnsibleError
-from ansible.module_utils.six import with_metaclass
+from ansible.plugins import AnsiblePlugin
-from ansible.module_utils._text import to_bytes
+
 
 try:
     from ncclient.operations import RPCError
@@ -47,7 +47,7 @@ def ensure_connected(func):
     return wrapped
 
 
-class NetconfBase(with_metaclass(ABCMeta, object)):
+class NetconfBase(AnsiblePlugin):
     """
     A base class for implementing Netconf connections