refactor: Use dataclasses for configuration/options and automate schema generation

[pawamoy]

TODO

• update mkdocstrings schema to point at new handler schema
• update master to main in mkdocs-material repo (https://github.com/squidfunk/mkdocs-material/blob/45f60a66903105d7a2fcb2a1ad64c3b347723f42/docs/schema/plugins.json#L117)
• Griffe extension to fetch fields' descriptions
• Test that assert all options are rendered in the docs (check autorefs' URL map)