Generate a D-Bus GUID that can be used with e.g. g_dbus_connection_new().
See the D-Bus specification regarding what strings are valid D-Bus GUIDs. The specification refers to these as ‘UUIDs’ whereas GLib (for historical reasons) refers to them as ‘GUIDs’. The terms are interchangeable.
Note that D-Bus GUIDs do not follow RFC 4122.
Available since: 2.26