Give access to the Point chart coordinates in draw functions to IntersectionPoint, SelectionHighlightPoint and SelectionHighlightPopUp

[TheOneTheOnlyJJ]

As the title suggests, the draw functions in the mentioned classes should give access to the actual data Point coordinates, not just the canvas location coordinates.

Adding a new Point method, getCanvasCoordinates, would enable passing the Point to these functions and allow access to the canvas coordinates.

My use case is applying a color gradient to both the SelectionHighlightPoint and SelectionHighlightPopUp, depending on the chart y value. However, I can only access the canvas y coordinate, so cannot properly calculate the linear interpolation (lerp) factor depending on the chart y coordinate.