MAPG-203 add new table and model for multi_room

database/migrations/structure/20210318_2136_multiplayer.sql

@@ -0,0 +1,9 @@
+CREATE TABLE `multi_rooms` (
+  `id` int(10) unsigned NOT NULL AUTO_INCREMENT,
+  `room_id` varchar(6) NOT NULL,
+  `state` text NOT NULL,
+  `members` text NOT NULL,
+  `updated` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP,
+  PRIMARY KEY (`id`),
+  UNIQUE KEY `room_id` (`room_id`)
+) ENGINE = InnoDB DEFAULT CHARSET = utf8mb4;