Add highlightBy feature for ChartTooltip

[marshallpete]

Provide a general summary of the feature here

Add a the ability to specify which marks should be highlighted on hover. Currently, hovering only highlights the hovered item. It would be useful to be able to highlight by item, dimension, series, or a list of custom keys.

🤔 Expected Behavior?

highlightBy="item" should be the default to prevent breaking changes.
highlightBy="dimension" will highlight by the dimension key set on the parent mark.
highlightBy="series" will highlight by rscSeriesId.
highlightBy={['period', 'event']} will highlight all points (bars etc.) that have the same period and event values as the highlighted point.

💁 Possible Solution

Add a new id called rscGroupId to any dataset that has highlightBy set to an array. This will join the key values together like we do for rscSeriesId.
Add highlight ruled for highlightedGroup like we do for highlightedSeries and highlightedItem.

🔦 Context

When highlighting a point on a time compare plot, we want to highlight both the current point and the associated past point.

💻 Examples

No response

🧢 Your Company/Team

Adobe/Product Analytics