add missing file from 016e90f

Author: endel

test/codegen/sources/PlainSchemaMap.ts

@@ -0,0 +1,12 @@
+import { schema } from "@colyseus/schema";
+
+export const Player = schema({
+    x: "number",
+    y: "number",
+  });
+
+export const MyRoomState = schema({
+    mapWidth: "number",
+    mapHeight: "number",
+    players: { map: Player },
+});