oka: not tested yet
- Introduced `Invitation` entity, table schema, and repository.
- Added `InvitationController` with APIs for creating, resolving, and accepting invitations.
- Implemented `InvitationService` to handle invitation workflows, including token generation and validation.
- Created unit tests for controller, service, and repository layers.
- Added support for patient-subject relationships with `PatientSubject` entity and repository.
- Updated `PatientAccessChecker` to handle subject-based access control.
- Extended Keycloak provisioning service for invitation role management.
- Updated database migrations to include invitations and patient-subject tables.
- Enhanced security configuration to permit invitation resolution API.
- Updated build scripts and dependencies for testing support.
