testing: Add tkm/xfrmproxy-rekey scenario

Similar to the xfrmproxy-expire scenario but here the TKM host is the
responder to a rekeying.

testing/tests/tkm/xfrmproxy-rekey/pretest.dat

@@ -0,0 +1,12 @@
+sun::ipsec start
+moon::rm /etc/ipsec.secrets
+moon::tkm_cfgtool -c /etc/tkm/tkm.conf -i /etc/ipsec.conf -t /etc/tkm/tkm.bin -s /usr/local/share/tkm/tkmconfig.xsd
+moon::cat /etc/ipsec.conf
+moon::tkm_keymanager -c /etc/tkm/tkm.bin -k /etc/tkm/moonKey.der -r /etc/tkm/strongswanCert.der >/tmp/tkm.log 2>&1 &
+moon::expect-file /tmp/tkm.rpc.ike
+moon::DAEMON_NAME=charon-tkm ipsec start
+moon::expect-file /tmp/tkm.rpc.ees
+moon::xfrm_proxy >/tmp/xfrm_proxy.log 2>&1 &
+moon::DAEMON_NAME=charon-tkm expect-connection conn1
+sun::expect-connection host-host
+moon::ping -c 3 192.168.0.2