Enable selecting language on world

[alexgarel]

What

While every language should be available on https://world.openfoodfacts.org/

• if we are on https://world.openfoodfacts.org/ we only see english (language drop-down is not active)
• if we are on https://world-fr.openfoodfacts.org/, language drop-down is hidden !)

Steps to reproduce the behavior

1. Go to https://world.openfoodfacts.org/
2. See that you can't select any language (only English is present)

4. Go to https://world-fr.openfoodfacts.org/
5. No language selector appears

Expected behavior

We should be able to select any language

Why

Non speaking english people might land on https://world.openfoodfacts.org/ or want to use it to access products.

Technical clue

This happens in Display.pm line 7308 as we fill $langs