Provide and import code lists

At the moment we request admins to manually import all required code lists.

This could easily be automated by packaging the code lists with this app and importing them after install or migrate, in case they're missing.

Code lists are available at the links mentioned in REAME.md or at https://ec.europa.eu/digital-building-blocks/sites/download/attachments/467108974/cef-genericodes-2025-05-15.zip