k8s: handle `fail_json` API from inventory plugin (#59)

Fixes: https://github.com/ansible-collections/kubernetes.core/issues/57

plugins/module_utils/exceptions.py

@@ -0,0 +1,11 @@
+# -*- coding: utf-8 -*-
+# Copyright: (c) 2021, Ansible Project
+# GNU General Public License v3.0+ (see COPYING or https://www.gnu.org/licenses/gpl-3.0.txt)
+
+from __future__ import absolute_import, division, print_function
+
+__metaclass__ = type
+
+
+class K8sInventoryException(Exception):
+    pass