Enhance tooltips on Row Col Chart

[Brian Lewis]

Changes for more effective communication from the tooltip:

1. Support a callback to the parent component, using tooltipper binding
2. Improved tooltip in percent formats: show both percentage and actual value e.g. 16 - 37.4%
3. Improved tooltip in pie formats: show both percentage and actual value e.g. 16 - 37.4% remove unnecessary series label value

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[Brian Lewis]

feat(charts): tooltips: enhanced default tooltips in rowcolchart; implement tooltip callback , show % on axis in percent layouts

Resolves #832

→ <<cset 648ca58c026e>>