constructor functions are ugly, because code is running before
main() starts. Instead, as the registration code for NMSetting types
is insid the GType constructor, we just need to ensure at the
right place, that the GType was created.
The right place here is _register_settings_ensure_inited(), because
that is called before we need the registration information.
It is safer to enable send-sci by default because, at the cost of
8-byte overhead, it makes MACsec work over bridges (note that kernel
also enables it by default). While at it, also make the option
configurable.
https://bugzilla.redhat.com/show_bug.cgi?id=1588041
The new NMSettingMacsec contains information necessary to establish a
MACsec connection. At the moment we support two different MACsec
modes, both using wpa_supplicant: PSK and EAP.
PSK mode is based on a static CAK key for the MACsec key agreement
protocol, while EAP mode derives keys from a 802.1x authentication and
thus requires the presence of a NMSetting8021x in the connection.
