website.favicon key is not parsed as markdown (possibly other keys)

[mcanouil]

From #2865 (comment).

Expected behaviour: keys under website to be read/parsed as markdown.
Current behaviour: <link href="./{{< var favicon >}}" rel="icon">

• quarto create project website issue6455

• _variables.yml

favicon: /images/favicon.png

• _quarto.yml

project:
  type: website

website:
  title: "Issue6455"
  favicon: "{{< var favicon >}}"
  navbar:
    left:
      - href: index.qmd
        text: Home
      - about.qmd

format:
  html:
    theme: cosmo
    css: styles.css
    toc: true

[mcanouil]

In some aspects, it's related to:

• Navbar - tools - text doesn't render markdown #6359