[Maps] Allow implementers of ITooltipProperty to return React-DOM for the tooltip-value

[thomasneirynck]

Describe the feature:

The public API for ITooltipProperty should not expose getHtmlDisplayValue, and rather have implementers return React-dom.

So something like this instead:

ITooltipProperty.renderDisplayValue(): ReactElement<any> | null;

This is more safe.

Having to plugin raw-html as the base-case was less of an issue when all code was internal to Maps, and there was a guarantee that all implementations of ITooltipProperty.getHtmlDisplayValue would only use Kibana's core Field-formatters. Allowing raw-html should only be for values from the Kibana field-formatters and not for any other implementation (especially not 3rd party ones).

This was raised by #126007 (review)

[elasticmachine]

Pinging @elastic/kibana-gis (Team:Geo)