Add an optional communications country field and language field so that we can have better email campaigns

[teolemon]

Problem

• A lot of users don't have a country field and language field (before we assigned one automatically)
• Add an optional editable communications country field and language field so that we can have better email campaigns
• In a future issue, we may implement an API/System to nudge users into updating it, so that eventually we get 100% of users with a language and country

### Tasks
- [ ] https://github.com/openfoodfacts/openfoodfacts-server/issues/8748
- [ ] https://github.com/openfoodfacts/openfoodfacts-server/issues/8749

Part of

• 5809

[github-actions[bot]]

This issue has been open 90 days with no activity. Can you give it a little love by linking it to a parent issue, adding relevant labels and projets, creating a mockup if applicable, adding code pointers from https://github.com/openfoodfacts/openfoodfacts-server/blob/main/.github/labeler.yml, giving it a priority, editing the original issue to have a more comprehensive description… Thank you very much for your contribution to 🍊 Open Food Facts

[alexgarel]

@teolemon I'm not sure if new language / country field fill this need.