implement show/hide layer with scripting

front/src/Api/Events/LayerEvent.ts

@@ -0,0 +1,10 @@
+import * as tg from "generic-type-guard";
+
+export const isLayerEvent =
+    new tg.IsInterface().withProperties({
+        name: tg.isString,
+    }).get();
+/**
+ * A message sent from the iFrame to the game to show/hide a layer.
+ */
+export type LayerEvent = tg.GuardedType<typeof isLayerEvent>;