[Feature]: Support links in MDX frontmatter

[knowler]

What is the new or updated feature that you are suggesting?

Currently, meta works in MDX frontmatter. It would be great if links worked the same way. Following YAML syntax it would look something like this:

---
meta:
  title: Welcome to the site
  description: Hello, World!
links:
  - rel: stylesheet
    href: "/welcome.css"
    media: "(prefers-reduced-motion: no-preference)"
---

Why should this feature be included?

While it is likely that Markdown content will share a single stylesheet which can be set in the layout root, sometimes a blog post or page might need to include a stylesheet for something specific included in the content. Currently, there is no way to do this other than include a <link> tag in the Markdown.