Make backend functionality useable as libraries

[westei]

To foster code reuse of the service and storage layer functionality of the MORE backend it is important to allow code reuse of the service and storage layer.

Tasks:

• Split the studymanager module in two parts
  • the Application Module: Spring Application, Config, Auth, Controller
  • the services module: Repositories, Services, Cron Tasks, ...
• Configure deployment of Maven Artefacts on the Github Artifactory
  • Extend Project Configuration
  • Extend the Pipeline to deploy Artefacts on Tags

This will allow to use backend functionality in other MORE related projects (e.g. the Gateway). To centralize Database related functionality so that changes in the Database schema do not require code changes in multiple repositories.