LibGUI: Implement attributes for windows

Windows can now change whether they have title bar, rounded corners,
alpha channel and whether they are movable. Also windows can also change
their own position

userspace/programs/WindowServer/Utils.h

@@ -29,6 +29,8 @@ struct Rectangle
 
 	BAN::Optional<Rectangle> get_overlap(Rectangle other) const
 	{
+		if (height == 0 || width == 0 || other.width == 0 || other.height == 0)
+			return {};
 		const auto min_x = BAN::Math::max(x, other.x);
 		const auto min_y = BAN::Math::max(y, other.y);
 		const auto max_x = BAN::Math::min(x + width, other.x + other.width);