testing: add a testcase for plain XAuth RADIUS authentication

testing/tests/ikev1/xauth-rsa-radius/posttest.dat

@@ -0,0 +1,5 @@
+moon::ipsec stop
+carol::ipsec stop
+alice::killall radiusd
+moon::iptables-restore < /etc/iptables.flush
+carol::iptables-restore < /etc/iptables.flush