Get persistence of DomainBase actually working (#438)

* Get persistence of DomainBase actually working

Fix all of the existing problems with DomainBase persistence:
- Remove "final" keywords on getters that cause errors during startup.
- Remove Transient from creationTime (since there's a converter for
  CreateAutoTimestamp)
- Fix DesignatedContext persistence so that it only creates a single table.
  This is a lot more efficient given that these are many-to-one with their
  domains.
- Add a flyway script, update the golden schema.
- Create a unit test, add it to the integration test suite.

* Changes request in review

* Regenerated generated schema file.

* Changes for review

* Persist status value enum set

* Changes in response to review

* Changes requested in review

* Fixes for #456

* Rename Domain "status" column to "statuses"

db/src/main/resources/sql/flyway/V15__add_epp_resources.sql

@@ -0,0 +1,44 @@
+-- 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.
+
+    create table "Domain" (
+       repo_id text not null,
+        creation_client_id text,
+        creation_time timestamptz,
+        current_sponsor_client_id text,
+        deletion_time timestamptz,
+        last_epp_update_client_id text,
+        last_epp_update_time timestamptz,
+        statuses text[],
+        auth_info_repo_id text,
+        auth_info_value text,
+        fully_qualified_domain_name text,
+        idn_table_name text,
+        last_transfer_time timestamptz,
+        launch_notice_accepted_time timestamptz,
+        launch_notice_expiration_time timestamptz,
+        launch_notice_tcn_id text,
+        launch_notice_validator_id text,
+        registration_expiration_time timestamptz,
+        smd_id text,
+        subordinate_hosts text[],
+        tld text,
+        primary key (repo_id)
+    );
+
+create index IDX8nr0ke9mrrx4ewj6pd2ag4rmr on "Domain" (creation_time);
+create index IDX8ffrqm27qtj20jac056j7yq07 on "Domain" (current_sponsor_client_id);
+create index IDX5mnf0wn20tno4b9do88j61klr on "Domain" (deletion_time);
+create index IDX1rcgkdd777bpvj0r94sltwd5y on "Domain" (fully_qualified_domain_name);
+create index IDXrwl38wwkli1j7gkvtywi9jokq on "Domain" (tld);