perf(vx-tooltip): use useCallback in useTooltip

[williaster]

🚀 Enhancements

When using useTooltip introduced in #631 I noticed that passing showTooltip or hideTooltip to a child component causes unnecessary and potentially expensive render cascades / child updates even though tooltipLeft, tooltipTop, or tooltipData didn't change.

This should be fixable by using the useCallback hook, where the callbacks are not instantiated each render, and thus PureComponents or React.memoized components should not update unless tooltipLeft, tooltipTop, or tooltipData update.

@kristw @hshoff
cc @ptmx