Commit contains all backend tasks for the project ramp-up phase.

[TOB-97] chor: Add initial backend project setup.

[TOB-106] feat: basic session and version REST-IF.

- added /userinfo interface that provides user details and roles
- added /keepalive-session interface that extends jwt validity
- added /versioninfo interface that provides service name and version
- added /logout interface to invalidate the jwt token

[TOB-106] feat: basic session and version REST-IF.

- added openapi.yaml containing basic interface definition
- cleaned up response types of the basic interface implementation to match the definition

[TOB-106] feat: basic session and version REST-IF.

- added deploy folder containing a keycloak test user setup script
- added role guards for /logout, /userinfo, /version and  /logout interfaces

[TOB112, TOB113, TOB114] feat: Dashboard Backend.

- added jpa database models for TblStatement, TblContact and
  TblAttachment
- added TblStatement...