feat: fontsource provider

[qwerzl]

I've explored other font providers, looks like fontsource is also quite promising.

Currently most of its fonts are from Google Fonts, along with some icons and some other fonts. It's also the service that Cloudflare Fonts is fetching from.

@danielroe Would you like to include this font provider? If so, I'd like to work on it.

Docs: https://fontsource.org/docs

[danielroe]

I would love that! It's a bit trickier because of the distribution method but ideas welcome! 🙏