A `JuiceStream` holds a legacy `SliderPath` as the representation of the path.
However, the `SliderPath` representation is difficult to work with because `SliderPath` works in 2D position, while osu!catch works in `(time, x)` coordinates.
This `JuiceStreamPath` represents the path in a more convenient way, a polyline connecting list of `(distance, x)` vertices.
