[BarChart] Support group and stack layout at same time

[techniq]

While we support

• <BarChart series={...} seriesLayout="group">
• <BarChart series={...} seriesLayout="stack">

it would be nice to come up with an API to defined both of these on the same BarChart and handle the data processing within BarChart like we do for the Chart-based example.

[techniq]

Resolved via #901

Examples:

• wide data
  • https://www.layerchart.com/docs/components/BarChart/group-stack-series (using x1 scale (group) + stack series)
  • https://www.layerchart.com/docs/components/Chart/facet-annotation (using facet (fx / fy) + stack series
• long data
  • https://www.layerchart.com/docs/components/BarChart/group-stack-long-data (x1 scale (group) + color (c) scale)
  • https://www.layerchart.com/docs/components/BarChart/facet-stack-long-data (using facet (fx / fy) + color(c) scale)