Refactor background and starry sky layer scripts; move to new directory structure

world/background/starry_sky_layer.gd

@@ -0,0 +1,11 @@
+class_name StarrySkyLayer extends Parallax2D
+
+var Background_Image_Size: Vector2 = Vector2.ZERO
+var Stars: Array = []
+
+const BACKGROUND_COLOR: Color = Color.TRANSPARENT
+
+func _draw():
+    draw_rect(Rect2(Vector2.ZERO, Background_Image_Size), BACKGROUND_COLOR)
+    for star in Stars:
+        draw_circle(star.coords, 2, star.color)