Translations for css formal definitions

[argl]

Description

Adds translations for the mdn-data-free version of rari. Existing translations on the formal definition values cannot be carried over, so there is a new translations file with only en-US values pre-filled and the rest auto-translated for a baseline.

Motivation

Remove mdn-data dependency from the publishing pipeline.

Additional details

This is compatible with the old and the new approach to formal definitions. Before merging the rari-part of this, nothing will change on the output.

Related issues and pull requests

See related rari PR: https://github.com/mdn/rari/pull/390