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:

letcrazyMarker=
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:

letlabels,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