AKModel + AKSubmissin: Introduce Types

The Summer KIF 2025 will be held together with the KoMa, requiring a way to attach additional information to AKs wether this AK is a KIF-AK, a KoMa-AK or both. This should be implemented by creating a re-usable AKType model that could be used for other type information (e.g., on the format of an AK) in the future, too.