support grouped bars in timeseries chart
e.g. by rendering bars of the same date next to each other instead of behind each other.
https://www.d3-graph-gallery.com/graph/barplot_grouped_basicWide.html
e.g. by rendering bars of the same date next to each other instead of behind each other.
https://www.d3-graph-gallery.com/graph/barplot_grouped_basicWide.html