(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/1592261300044-DocRemovedAt.ts

@@ -0,0 +1,26 @@
+import {nativeValues} from "app/gen-server/lib/values";
+import {MigrationInterface, QueryRunner, TableColumn, TableIndex} from "typeorm";
+
+export class DocRemovedAt1592261300044 implements MigrationInterface {
+
+  public async up(queryRunner: QueryRunner): Promise<any> {
+    for (const table of ['docs', 'workspaces']) {
+      await queryRunner.addColumn(table, new TableColumn({
+        name: 'removed_at',
+        type: nativeValues.dateTimeType,
+        isNullable: true
+      }));
+      await queryRunner.createIndex(table, new TableIndex({
+        name: `${table}__removed_at`,
+        columnNames: ['removed_at']
+      }));
+    }
+  }
+
+  public async down(queryRunner: QueryRunner): Promise<any> {
+    for (const table of ['docs', 'workspaces']) {
+      await queryRunner.dropIndex(table, `${table}__removed_at`);
+      await queryRunner.dropColumn(table, 'removed_at');
+    }
+  }
+}