Technical Story: Implement /roles endpoint

[MasterEvarior]

Description

For each calculation there is an associated role, which can be accessed from the backend. Each role has a name and can either be a leadership or an individual contributer role.

Each role is saved in a roles table in the database, the properties of which can be seen on the DB diagram.

The API should support all CRUD operations, as defined by the Open API specificiation. The general guidelines set out for the API should also be followed.

It may be possible to export the roles from PTime, to make the initial data import easier.

Acceptance Criteria

• API is implemented as per specification
• Unit tests are written
• Integration tests are written
• DB schema is migrated with Flyway
• The initial data get inserted during the DB migration
• The dev database also has some initial data for testing
• All tests in the CI are OK

Additional Information

• A list of all current roles can be found here
• Ignore "stufenlose" roles
• JPA Soft Delete