testing: Add a test scenario for make-before-break reauth using a virtual IP

testing/tests/ikev2/reauth-mbb-virtual-ip/hosts/moon/etc/strongswan.conf

@@ -0,0 +1,5 @@
+# /etc/strongswan.conf - strongSwan configuration file
+
+charon {
+  load = aes des sha1 sha2 md5 pem pkcs1 gmp random nonce x509 curl revocation hmac xcbc stroke kernel-netlink socket-default updown
+}