(core) move home server into core

Summary: This moves enough server material into core to run a home server.  The data engine is not yet incorporated (though in manual testing it works when ported).

Test Plan: existing tests pass

Reviewers: dsagal

Reviewed By: dsagal

Differential Revision: https://phab.getgrist.com/D2552

app/gen-server/migration/1591755411755-OrgHost.ts

@@ -0,0 +1,17 @@
+import {MigrationInterface, QueryRunner, TableColumn} from "typeorm";
+
+export class OrgHost1591755411755 implements MigrationInterface {
+
+  public async up(queryRunner: QueryRunner): Promise<any> {
+    await queryRunner.addColumn('orgs', new TableColumn({
+      name: 'host',
+      type: 'varchar',
+      isNullable: true,
+      isUnique: true
+    }));
+  }
+
+  public async down(queryRunner: QueryRunner): Promise<any> {
+    await queryRunner.dropColumn('orgs', 'host');
+  }
+}