Implement the Core Data repositories

[official-Cromatin]

The objective of this task is to establish „Repositories“ for each Entity, enabling CRUD operations and application-specific data loading.

Initially, each Repository will possess a function to create new objects.

In the case of entities with relationships to other entities, the Repository will establish both the direct and inverse relationships.

This approach ensures data integrity and consistency.

[official-Cromatin]

One example to this approach being the AllergenRepository:

final class AllergenRepository {
    static func createAllergen(
        name: String,
        meal: MealEntity,
        context: NSManagedObjectContext
    ) -> AllergenEntity {
        let allergen = AllergenEntity(context: context)
        allergen.name = name
        
        allergen.meal = meal
        return allergen
    }
}

Notice that the Repository is stateless, meaning it doesn’t maintain a context associated with it.
However, this might change in the future.