Automatically fetch Gaia-X credential schemas from Registry/GXDCH
Going beyond #199 (closed), rather than just, from time to time, copying over the latest released schemas from the Gaia-X Registry / GXDCH into the XFSC Catalogue Repository and thus the defaults of any new deployed instance, we might enable the XFSC Catalogue to actively fetch "the latest schemas" from the Registry / GXDCH.