Handle properties that can be either single or multiple values

[kMutagene]

This PR adds internal utils to set properties that can be either set by a single value or an array of values on the plotly.js side. We do not use a DU for this because it would increase verbosity too much. See #192

I also implemented this for bar traces and the Marker object (where this was most requested) for reference. Implementing this for all traces/charts is a huge chunk of work and may be too much to do before 2.0 release. Progress is tracked in #196

fixes #191

[kMutagene]

Example of what is now possible:

let crazyMarker =
    Marker.init(
        MultiSymbols = [
            StyleParam.MarkerSymbol.ArrowBarDown
            StyleParam.MarkerSymbol.Modified(StyleParam.MarkerSymbol.DiamondCross, StyleParam.SymbolStyle.OpenDot)
            StyleParam.MarkerSymbol.Modified(StyleParam.MarkerSymbol.Square, StyleParam.SymbolStyle.Open)
            StyleParam.MarkerSymbol.Modified(StyleParam.MarkerSymbol.Hexagon2, StyleParam.SymbolStyle.Dot)
        ],
        MultiSizes = [50;60;100;70],
        MultiOpacities = [0.3; 0.6; 0.9; 1.],
        Color = Color.fromColorScaleValues [0.; 0.5; 1.; 0.8],
        Colorscale = StyleParam.Colorscale.Viridis,
        ShowScale = true
    )

Chart.Point [1,1; 2,2; 3,3; 4,4]
|> Chart.withMarker crazyMarker
|> Chart.show

[kMutagene]

More goodness:

let labels, values = 
    [
        "A", 1
        "B", 3
        "C", 2
        "D", 4
        "E", 6
        "F", 5
        "G", 7
        "H", 8
    ]
    |> List.unzip

Chart.Bar(
    keys = labels, 
    values = values,
    Color = Color.fromColorScaleValues values
)
|> Chart.withMarkerStyle(
    Colorscale = StyleParam.Colorscale.Viridis,
    ShowScale = true,
    Pattern = Pattern.init(
        MultiShapes = [
            StyleParam.PatternShape.None 
            StyleParam.PatternShape.DiagonalDescending
            StyleParam.PatternShape.DiagonalAscending
            StyleParam.PatternShape.DiagonalChecked
            StyleParam.PatternShape.HorizontalLines
            StyleParam.PatternShape.VerticalLines
            StyleParam.PatternShape.Checked
            StyleParam.PatternShape.Dots
        ]
    )
)
|> Chart.show