Support military travelers in Direct natively

Military travelers paying with a Government Travel Charge Card (GTCC / IBA) are legally exempt from state and city lodging tax on federally funded stays, and they require Defense Travel System (DTS)-compliant travel receipts. Using Direct as the merchant of record, allow a host, or, better, a military traveler, to designate a stay as one of these kinds, with required documentation. If the service member is verified, do not charge taxes, and provide the traveler a DTS-compliant receipt. This request is to build native support for this use case into Hospitable’s Direct features as a long-term solution to the workaround described by https://feedback.hospitable.com/p/convert-a-direct-inquiry-into-a-manual-booking-one-click