back/migration command: add log to show that we are rolling back a migration and which one

src/db/MysqlConnectionManager.ts

@@ -242,6 +242,9 @@ export default class MysqlConnectionManager {
                     if (args.length > i + 1) {
                         migrationId = parseInt(args[i + 1]);
                     }
+
+                    logger.info('Rolling back migration', migrationId);
+
                     await this.prepare(false);
                     await this.rollbackMigration(migrationId);
                     return;