ipsec: add nmstate ipsec tests bits
Import nmstate based libreswan tests. Very quick test set that uses NM and it's libreswan plugin checking that we can set interface name, set DPD parameters, and use RSA key management.
https://issues.redhat.com/browse/RHEL-16899 https://issues.redhat.com/browse/RHEL-16900 https://issues.redhat.com/browse/RHEL-17260