Support the nmstate network state configuration

The users want to apply the nmstate network state configuration to the
interface directly through the role, which necessitates the less
complexity of the network configuration and allows the partial
configuration on the network.

To warrant that the users are capable to apply the nmstate network state
configuration, add the support for the `network_state` variable.

Signed-off-by: Wen Liang <liangwen12year@gmail.com>

library/network_state.py

@@ -0,0 +1,74 @@
+#!/usr/bin/python
+# -*- coding: utf-8 -*-
+# SPDX-License-Identifier: BSD-3-Clause
+
+from __future__ import absolute_import, division, print_function
+
+__metaclass__ = type
+
+DOCUMENTATION = r"""
+---
+module: network_state
+version_added: "2.9"
+short_description: module for network role to apply network state configuration
+description:
+    - This module allows to apply the network state configuration through nmstate,
+      https://github.com/nmstate/nmstate
+options:
+    desired_state:
+        description: Nmstate state definition
+        required: true
+        type: dict
+author: "Wen Liang (@liangwen12year)"
+"""
+
+RETURN = r"""
+state:
+    description: Network state after running the module
+    type: dict
+    returned: always
+"""
+
+from ansible.module_utils.basic import AnsibleModule
+import libnmstate  # pylint: disable=import-error
+
+
+class NetworkState:
+    def __init__(self, module, module_name):
+        self.module = module
+        self.params = module.params
+        self.result = dict(changed=False)
+        self.module_name = module_name
+        self.previous_state = libnmstate.show()
+
+    def run(self):
+        desired_state = self.params["desired_state"]
+        libnmstate.apply(desired_state)
+        current_state = libnmstate.show()
+        if current_state != self.previous_state:
+            self.result["changed"] = True
+
+        self.result["state"] = current_state
+
+        self.module.exit_json(**self.result)
+
+
+def run_module():
+    module_args = dict(
+        desired_state=dict(type="dict", required=True),
+    )
+
+    module = AnsibleModule(
+        argument_spec=module_args,
+    )
+
+    network_state_module = NetworkState(module, "network_state")
+    network_state_module.run()
+
+
+def main():
+    run_module()
+
+
+if __name__ == "__main__":
+    main()