testing: Add tkm xfrmproxy-expire test

This test asserts that the handling of XFRM expire messages from the
kernel are handled correctly by the xfrm-proxy and the Esa Event Service
(EES) in charon-tkm.

testing/tests/tkm/xfrmproxy-expire/hosts/sun/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
+}