New render tooltip prop to allow for more customization

[gabrieljablonski]

Closes #949

Signature:

render?: (render: {
  content: string | null
  activeAnchor: HTMLElement | null
}) => ChildrenType

Usage example:

<a data-tooltip-id="my-tooltip" data-tooltip-content="my-content" />
<Tooltip
  id="my-tooltip"
  render={({ content, activeAnchor }) => (
    <>
      content={content} from anchor with id={activeAnchor?.id}
    </>
  )}
/>

content comes from data-tooltip-content on the anchor.

[danielbarion]

looks good to me! great job :)

[j-greig]

Got this working with an API call inside the tooltip to fetch live data, nice 🤝