Related to https://github.com/spantaleev/matrix-docker-ansible-deploy/issues/3841
Most of the preparation for this was done by Suguru Hirahara (https://github.com/luixxiul).
I've merely reorganized/polished the scripts and instructions in the `i18n/` directory.
While translations can happen even now, more work is necessary to
- make the translation flow better (integrating Weblate), etc.
- restore the Github Actions workflows that Suguru Hirahara had already developed to
adapt them to our new workflow
