Add furigana/ruby characters support

[TheHanziChauvanist]

Description

I think that we should add furigana/ruby support into Quarto, and it needs to be East Asian language agnostic, which means that we can create Arabic/English furigana as well as Japanese/English furigana. The syntax can be taken from here:

https://github.com/iltrof/furigana-markdown-it

[mcanouil]

There is at least one Pandoc filter that you can use for that: https://github.com/waldeir/pandoc-filter-furigana.

filters:
  - handleFurigana.py

You can also adapt or create your own filter and packaged it as a Quarto extension: https://quarto.org/docs/extensions/filters.html