- Arranged commit before merge
- Replaced string-based timestamps by context.Timestamp
- Created helper functions to convert timestamps string from/to float
- Arranged requirements to meet dependencies of converter functions

- defined unified constants for all micro-services
- defined common settings getter methods
- defined generic gRPC servicer
- defined generic Rest servicer
- defined common MockServicer for Monitoring component
- removed old common/tests MockService class; to be replaced by new generic gRPC servicer
- minor code formatting/styling

- 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)