Add vega-lite as embedding object

[aborruso]

Hi,
it would be great to have in quarto for vega-lite, something like the Mermaid diagrams.

To write something like

``` {vega-lite}
{
  "data": {
    "values": [
      {"a": "C", "b": 2}, {"a": "C", "b": 7}, {"a": "C", "b": 4},
      {"a": "D", "b": 1}, {"a": "D", "b": 2}, {"a": "D", "b": 6},
      {"a": "E", "b": 8}, {"a": "E", "b": 4}, {"a": "E", "b": 7}
    ]
  },
  "mark": "point",
  "encoding": {
    "x": {"field": "a", "type": "nominal"}
  }
}
```

to get

Thank you

[cscheid]

Agreed, vega + vega-lite support would indeed be excellent. We'll try to do it in the next 3-6 months.

[ijlyttle]

If you are using the knitr engine, the vegadown package might work here.

It was a bit of an experiment, and hasn't made it to CRAN (prob. won't if Vega gets first-class support in Quarto). Maybe it can fit the need in the meantime.

[aborruso]

If you are using the knitr engine, the vegadown package might work here.

thank you very much

[mcanouil]

Closing in favour of #2885