In continuation of the theme, the removal of user settings services
means that the distinction between NMSysconfigConnection and
NMExportedConnection is no longer needed. Merge NMExportedConnection
into NMSysconfigConnection.
Much as with nm-remote-settings and nm-remote-settings-system, the
removal of user settings services means there is no more need for
separate interfaces for user and system settings services.
In libnm-glib, this commit merges everything in
nm-settings-system-interface into nm-settings-interface. Alongside with
that, we merge everything in the
org.freedesktop.NetworkManagerSettings.System DBus interface into
org.freedesktop.NetworkManagerSettings.