Convert DomainBase's contacts to VKeys (#574)

* Convert DomainBase's contacts to VKeys

Convert usage of DomainBase contacts from Key to VKey.  This is the same
change as done for nameserver hosts, as it affects all external interfaces.
As with nameserver hosts, we preserve the existing representation so as not to
afffect the datastore representation.

db/src/main/resources/sql/flyway/V24__domain_base_contacts.sql

@@ -0,0 +1,38 @@
+-- Copyright 2020 The Nomulus Authors. All Rights Reserved.
+--
+-- Licensed under the Apache License, Version 2.0 (the "License");
+-- you may not use this file except in compliance with the License.
+-- You may obtain a copy of the License at
+--
+--     http://www.apache.org/licenses/LICENSE-2.0
+--
+-- Unless required by applicable law or agreed to in writing, software
+-- distributed under the License is distributed on an "AS IS" BASIS,
+-- WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+-- See the License for the specific language governing permissions and
+-- limitations under the License.
+
+ALTER TABLE "Domain" ADD COLUMN admin_contact text;
+ALTER TABLE "Domain" ADD COLUMN billing_contact text;
+ALTER TABLE "Domain" ADD COLUMN registrant_contact text;
+ALTER TABLE "Domain" ADD COLUMN tech_contact text;
+
+alter table if exists "Domain"
+   add constraint fk_domain_admin_contact
+   foreign key (admin_contact)
+   references "Contact";
+
+alter table if exists "Domain"
+   add constraint fk_domain_billing_contact
+   foreign key (billing_contact)
+   references "Contact";
+
+alter table if exists "Domain"
+   add constraint fk_domain_registrant_contact
+   foreign key (registrant_contact)
+   references "Contact";
+
+alter table if exists "Domain"
+   add constraint fk_domain_tech_contact
+   foreign key (tech_contact)
+   references "Contact";