fix: "SubsurfaceViewer: colorAbove/colorBelow/colorNaN possibly not working? #2479"

[nilscb]

Added a few more properties to colormap layer.
See new stories under HillshadingLayer folder.
This will allow contour lines and hillshading directly in colormap layer.

Also added option to set clamp color. The previous behavior would clamp to colormap min and max value. This will give the option to clamp to a given fixed color. (or transparent)

New properties:

    // If true, draw contour lines.  Default false.
    contours: boolean;

    // If true, apply hillshading. Default false.
    hillshading: boolean;

    // Contour reference height. Default 0.
    contourReferencePoint: number;

    // Height between contour lines. Default 50.
    contourInterval: number;

    /**  Clamp colormap to this color at ends.
     * Given as array of three values (r,g,b) e.g: [255, 0, 0]
     * If not set or set to true, it will clamp to color map min and max values.
     * If set to false the clamp color will be completely transparent.
     */
    colorMapClampColor: Color | undefined | boolean;

    // Optional height map. If set hillshading and contourlines will be based on this map.
    heightMapUrl: string;

    // Min and max values of optional height map.
    // Defaults to "valueRange".
    heightValueRange: [number, number];

[nilscb]