Danger.vega() / Vega integration

[OAGr]

Vega and other chart libraries have a lot of complicated features that would take ages to replicate in Squiggle Components.

It seems useful to quickly experiment with complex charts, and use some specific ones for special purposes.

One way of doing this is to send Squiggle functions to observable, then make a dashboard there. Then maybe even allow embedding back to Squiggle Hub, to see it there. I've been wanting to do something like this (to more quickly experiment with functionality).

A much nicer (for a few reasons) solution would be to integrate some more complex graphing library into SquiggleHub. Maybe we could find some solution here that's doesn't require much integration/overhead.

https://vega.github.io/vega-lite/examples/#line-charts