SCSS support

One day we'd like to be able to parse SCSS.

> Ported from readme

- [ ] Is capable of interpreting SCSS files
- [ ] Produces a usable AST for:
- [ ] all [bootstrap][7] scss files
- [ ] all [foundation][9] scss files
- [ ] all [mini.css][11] scss files
- [ ] all [primer css][16] scss files
- [ ] all [bourbon][17] scss files

[1]: https://github.com/Boshen/oxc
[2]: https://github.com/romainmenke/css-tokenizer-tests
[3]: https://github.com/postcss/postcss-parser-tests
[4]: https://github.com/nathansmith/960-grid-system
[5]: https://github.com/animate-css/animate.css
[6]: https://github.com/joshuaclayton/blueprint-css
[7]: https://github.com/twbs/bootstrap
[8]: https://github.com/FortAwesome/Font-Awesome
[9]: https://github.com/foundation/foundation-sites/tree/develop/scss
[10]: https://github.com/inuitcss/inuitcss
[11]: https://github.com/Chalarangelo/mini.css/
[12]: https://github.com/argyleink/open-props
[13]: https://github.com/pure-css/pure/
[14]: https://meyerweb.com/eric/tools/css/reset/
[15]: https://github.com/tailwindlabs/tailwindcss
[16]: https://github.com/primer/css
[17]: https://github.com/thoughtbot/bourbon
[18]: https://github.com/stylelint/stylelint