Support for Shiny and learnr style questions

[ryjohnson09]

I'd love to ask questions using quarto-live similar to the learnr example found here: https://learnr-examples.shinyapps.io/ex-setup-r/#section-welcome

Things like multiple-choice and radio buttons.

Maybe this is already possible?

[georgestagg]

I agree this is a good idea, but I'm going to close this in favour of tracking the request as part of #9.

In the mean time, you can manually setup something similar to this using webR+OJS. The approach in #43 is pretty good:

```{webr}
#| edit: false
#| output: false
#| define:
#|   - ok_reponse
library(htmltools)
ok_reponse <- function(reponse, n) {
  if (is.na(reponse)) HTML("")
  else if (reponse == n) div(HTML("Correct ✓"), style = "color: green")
  else div(HTML("Incorrect ✗"), style = "color: red")
}
```

```{ojs}
//| echo: false
mutable ok_reponse = (reponse, n) => { return html`Loading...` };
viewof reponse = Inputs.radio(
  new Map([
    ["First choice.", 1],
    ["Second choice.", 2],
    ["Third choice", 3],
    ["Fourth choice.", 4]
  ])
);
ok_reponse(reponse, 2);
```

But clearly it would be better if these implementation details were automated away.