Groups persistence and logic

.../java/it/inaf/ia2/gms/authn/CustomAuthenticationData.java

...in/java/it/inaf/ia2/gms/authn/CustomIdTokenConverter.java

gms/src/main/java/it/inaf/ia2/gms/authn/LoginController.java

gms/src/main/java/it/inaf/ia2/gms/authn/SecurityConfig.java

gms/src/main/java/it/inaf/ia2/gms/authn/SessionData.java

...ain/java/it/inaf/ia2/gms/controller/GroupsController.java

...ava/it/inaf/ia2/gms/controller/GroupsModelController.java

...it/inaf/ia2/gms/controller/model/GroupsModelResponse.java

...java/it/inaf/ia2/gms/exception/UnauthorizedException.java

...src/main/java/it/inaf/ia2/gms/model/BaseModelRequest.java

...rc/main/java/it/inaf/ia2/gms/model/BaseModelResponse.java

...c/main/java/it/inaf/ia2/gms/model/CreateGroupRequest.java

gms/src/main/java/it/inaf/ia2/gms/model/GroupBreadcrumb.java

gms/src/main/java/it/inaf/ia2/gms/model/GroupNode.java

...c/main/java/it/inaf/ia2/gms/model/GroupsModelRequest.java

.../main/java/it/inaf/ia2/gms/model/GroupsModelResponse.java

gms/src/main/java/it/inaf/ia2/gms/model/Identity.java

gms/src/main/java/it/inaf/ia2/gms/model/IdentityType.java

gms/src/main/java/it/inaf/ia2/gms/model/PaginatedData.java

gms/src/main/java/it/inaf/ia2/gms/model/Permission.java