Add integration tests and fix nxos providers (#26913)

* fix issues with python3.x

* Add integration testa and fix for nxos_evpn_vni

* add nxos_evpn_vni to nxos.yaml

* fix get_vtp_config()

* add new integration tests

* fix rollback

* add integration test files

test/units/modules/network/nxos/test_nxos_vrf.py

@@ -47,6 +47,8 @@ class TestNxosVrfModule(TestNxosModule):
             output = list()
 
             for command in commands:
+                if isinstance(command, dict):
+                    command = command['command']
                 filename = str(command).split(' | ')[0].replace(' ', '_')
                 output.append(load_fixture('nxos_vrf', filename))
             return output