feat(#8): modularizing

modules/game-objects/camera.js

@@ -0,0 +1,12 @@
+import { GameObject } from "./game-object.js";
+
+export class Camera extends GameObject {
+  constructor({ map, x = 0, y = 0, width = 320, height = 240 }) {
+    super({ x, y });
+    this.map = map;
+    this.x = x;
+    this.y = y;
+    this.width = width;
+    this.height = height;
+  }
+}