Consider implementing `ContourData` to allow a more customized setting of x, y, z in contour plots

[allanleal]

Consider implementation of ContourData to allow a more customized setting of x, y, z:

fig.drawContour(
    ContourData()
        .x()
        .y()
        .z()
        .name()
        .x0()
        .dx()
        .y0()
        .dy(),
    ContourSpecs()
        .colorscale("Portland")
        .coloringModeFill()
        .coloringModeHeatmap()
        .numContours(20),
        .line(LineSpecs()
            .width(1)
            .color("white")));

Currently, only fig.drawContour(x, y, z, specs) is allowed.