Refactor project architecture to make ORM migration easier

[Lamroy95]

Change project structure, align some parts to clean architecture (services and models).
This will make it easier to migrate ORM from Tortoise to SQLAlchemy.

• Move database models into infrastructure layer (app.infrastructure.database.models)
• Separate data access logic from services and database models (maybe create Repos in app.infrastructure.database.repo)
• Isolate infrastructure layer: add DTOs and interfaces