OZG-3056: implement user id synchronisation

...-manager-server/src/main/java/de/itvsh/kop/user/User.java

...r/src/main/java/de/itvsh/kop/user/UserResourceMapper.java

...n/java/de/itvsh/kop/user/keycloak/KeycloakApiService.java

...de/itvsh/kop/user/keycloak/KeycloakUserRemoteService.java

...c/main/java/de/itvsh/kop/user/keycloak/KeycloakUtils.java

...n/java/de/itvsh/kop/user/keycloak/UserWithAttributes.java

...ver/src/main/java/de/itvsh/kop/user/sync/SyncService.java

...c/test/java/de/itvsh/kop/user/UserResourceMapperTest.java

...rver/src/test/java/de/itvsh/kop/user/UserTestFactory.java

...tvsh/kop/user/keycloak/KeycloakUserRemoteServiceTest.java

...st/java/de/itvsh/kop/user/keycloak/KeycloakUtilsTest.java

...tvsh/kop/user/keycloak/UserWithAttributesTestFactory.java

...test/java/de/itvsh/kop/user/sync/SyncSchedulerITCase.java

...c/test/java/de/itvsh/kop/user/sync/SyncServiceITCase.java

...src/test/java/de/itvsh/kop/user/sync/SyncServiceTest.java