- Complete rework of Database API
- Integration of Database API into Context
- Improvement of API

This commit is not a final implementation, just an intermediate backup.

Minor changes to prevent errors in GitLab CI pipeline. Still partial implementation of "slice" component skeleton.

- Initial (unfinished) version of Slice component
- Factorized and improved check methods from "device" and "service" components to align with "slice" component

Common / Context / Device / Service:
- Improvements in unitary testing
- Extended assertion validators tor testing
- Factorized service implementation code to improve testability, reusability and increase code coverage

Factorization of code between services and minor unitary testing improvements. (Not finished, it is just a backup)

This reverts merge request !3