Merge pull request 'OZG-6528-DateienLaden' (#3) from OZG-6528-DateienLaden into master

...ger-interface/src/main/protobuf/collaboration.model.proto

...n-manager-interface/src/main/protobuf/collaboration.proto

...de/ozgcloud/collaboration/CollaborationEventListener.java

...a/de/ozgcloud/collaboration/CollaborationGrpcService.java

.../java/de/ozgcloud/collaboration/CollaborationService.java

...ozgcloud/collaboration/common/grpc/ExceptionRunnable.java

...de/ozgcloud/collaboration/common/grpc/GrpcDownloader.java

...cloud/collaboration/CollaborationEventListenerITCase.java

.../ozgcloud/collaboration/CollaborationGrpcServiceTest.java

...de/ozgcloud/collaboration/CollaborationServiceITCase.java

...a/de/ozgcloud/collaboration/CollaborationServiceTest.java

...zgcloud/collaboration/common/grpc/GrpcDownloaderTest.java