[Feature]: Different number format for tooltips and Axis labels

[archiewood]

Description

The ability to use a different number format for the y axis vs the tooltip

What problem would this solve?

Often want to show more precision on the tooltip than the axis, for example

How should it work?

<BarChart
  data={orders_by_month}
  y=sales
  yFmt=usd1k
  yAxisLabelFmt=usd0k
/>