Quarto vignettes

[teunbrand]

This PR aims to fix #5760.

I think I did everything correctly, but I'd be wise for somebody with more experience with quarto to take a glance.

[teunbrand]

I think this gets stuck on r-lib/pkgdown#2821, so it might be best to wait for this until the next pkgdown version arrives on CRAN.

[teunbrand]

pkgdown seems to now work correctly, so I'm undrafting this PR

[thomasp85]

I'm quite fond of being able to set global chunk options in the front matter, e.g.

knitr:
  opts_chunk:
    collapse: false
    comment: "#>"

(from the plumber2 vignettes)

I think we should update our vignettes to move it

[teunbrand]

I'm quite fond of being able to set global chunk options in the front matter

I agree this is sensible.

There was an unexpected CI error on old windows, where I followed workaround mentioned here: quarto-dev/quarto-r#217 (comment)