[Stateless SG] Test if TCP packets with various conn state are allowed

In stateless SG there is no connection track so TCP packet of any type
should be allowed by SG. This patch adds test which spawns 2 vms,
connected to 2 different networks and the same router. Both vms are
using different stateless SGs. Finally test asserts that packets of any
of the TCP type (syn, ack, syn-ack, psh, rst, fin) sent from one of the
vms can reach second one.

Change-Id: I23a4b282c83101526af05aa309d578aecaef1fa9
diff --git a/neutron_tempest_plugin/scenario/base.py b/neutron_tempest_plugin/scenario/base.py
index 4d769dc..c8eddd1 100644
--- a/neutron_tempest_plugin/scenario/base.py
+++ b/neutron_tempest_plugin/scenario/base.py
@@ -675,3 +675,15 @@
         router = self.client.update_router(
             router['id'], **kwargs)['router']
         self.assertEqual(admin_state_up, router['admin_state_up'])
+
+    def _check_cmd_installed_on_server(self, ssh_client, server, cmd):
+        try:
+            ssh_client.execute_script('which %s' % cmd)
+        except SSH_EXC_TUPLE as ssh_e:
+            LOG.debug(ssh_e)
+            self._log_console_output([server])
+            self._log_local_network_status()
+            raise
+        except exceptions.SSHScriptFailed:
+            raise self.skipException(
+                "%s is not available on server %s" % (cmd, server['id']))