Chart hover tooltips are not accessible

[zac1st1k]

NVD3 version used:
1.8.6

Browser and OS used:
Chrome Mac OS

Live Example:
https://jsfiddle.net/zac1st1k/t8d3n57m/68/

Expected Behaviour:
Tooltip should be accessible. The triggering element should be focusable. The tooltip information should have ARIA roles to be announced by screen readers.

Present Behaviour:
Tooltip are not accessible. Triggering elements can not gain focus. No ARIA roles defined. No announcements from screen readers.

Screenshot:

Related doc:
https://allyjs.io/tutorials/focusing-in-svg.html
https://www.w3.org/WAI/ARIA/apg/patterns/tooltip/