Add options.interaction where options.hover and options.tooltips extend from

[kurkle]

Change controllers to provide that instead of hover.

Implements #5861

Pen to play with: https://codepen.io/kurkle/pen/yQdVjm

[simonbrunel]

Thanks @kurkle for your contribution. We tagged this feature for next major release because it may introduce breaking changes for external code. I see you added some logic to generate tooltips / hover from interactions but I think it doesn't work if you try to update interactions.* with new values and call chart.update() because tooltips and hover would already exist.

Also, it's not consistent with our fallback logic: we don't generate missing options but compute final values in place (e.g. if not tooltip.mode then fallback to interactions.mode). So for now, I would close this PR and plan this feature for v3.

[kurkle]

@simonbrunel oh, I now see. With consistent (and proper) fallback logic it would introduce breaking changes for external code. So closing this is ok for me.