nxos: Make sure config ends with a linefeed (#48465)

The config parser on NX-OS does not deal with configs that do not end
with a linefeed correctly which leads to various issues when the config
is loaded from startup-config upon reboot. Therefore, ensure that the
config returned is terminated by a linefeed.

lib/ansible/module_utils/network/nxos/nxos.py

@@ -145,7 +145,7 @@ class Cli:
             except ConnectionError as exc:
                 self._module.fail_json(msg=to_text(exc, errors='surrogate_then_replace'))
 
-            cfg = to_text(out, errors='surrogate_then_replace').strip()
+            cfg = to_text(out, errors='surrogate_then_replace').strip() + '\n'
             self._device_configs[cmd] = cfg
             return cfg