Transfer the valuable parts of the codebase to openfoodfacts-kotlin

[teolemon]

Problem

• We're not using this codebase as our main app anymore (at least for Open Food Facts)
• It would be a shame to stop using/maintaining this Kotlin codebase
• Transfer the valuable parts of the codebase to openfoodfacts-kotlin so that other apps can leverage it

[lonewolf2208]

Hey @teolemon I would like to work on this .

[VaiTon]

@lonewolf2208 it's a really big work. We should first decide how to implement the kotlin sdk (also for @teolemon). We have to decide if we want to do it from zero or take the API part from the application and move it to a new repository.