Translations: implement CI checks

[benoit74]

We need some CI checks for translations just like what we have on zimit-frontend:

https://github.com/openzim/zimit-frontend/blob/c5a8882724f551501ec0790719f8f746879e73eb/.github/workflows/QA.yml#L72-L92

This will help merge TranslateWiki PRs with much more confidence.