testing: Add ikev2/per-cpu-sas-encap-transport scenario

Tests transport mode and UDP encapsulation with random source ports.
Interestingly, the responder always uses the same SA to respond (maybe
due to the cache on the policy).

testing/tests/ikev2/per-cpu-sas-encap-transport/posttest.dat

@@ -0,0 +1,5 @@
+moon::swanctl --terminate --ike gw-gw 2> /dev/null
+moon::systemctl stop strongswan
+sun::systemctl stop strongswan
+moon::iptables-restore < /etc/iptables.flush
+sun::iptables-restore < /etc/iptables.flush