testing: Add an acert test using locally cached attribute certificates

testing/tests/ikev2/acert-cached/pretest.dat

@@ -0,0 +1,9 @@
+moon::iptables-restore < /etc/iptables.rules
+carol::iptables-restore < /etc/iptables.rules
+dave::iptables-restore < /etc/iptables.rules
+moon::ipsec start
+carol::ipsec start
+dave::ipsec start
+carol::sleep 1
+carol::ipsec up home
+dave::ipsec up home