Refactor REST API for structures

...org/openepics/names/repository/DeviceGroupRepository.java

.../org/openepics/names/repository/DeviceTypeRepository.java

.../org/openepics/names/repository/DisciplineRepository.java

...a/org/openepics/names/repository/SubsystemRepository.java

...org/openepics/names/repository/SystemGroupRepository.java

...java/org/openepics/names/repository/SystemRepository.java

...ain/java/org/openepics/names/rest/api/v1/IStructures.java

...org/openepics/names/rest/controller/ReportController.java

...openepics/names/rest/controller/StructuresController.java

...n/java/org/openepics/names/service/StructuresService.java

...ava/org/openepics/names/util/ValidateNameElementUtil.java

...rg/openepics/names/util/ValidateStructureElementUtil.java

...a/org/openepics/names/docker/StructuresDeviceGroupIT.java

...va/org/openepics/names/docker/StructuresDeviceTypeIT.java

...va/org/openepics/names/docker/StructuresDisciplineIT.java

...ava/org/openepics/names/docker/StructuresSubsystemIT.java

...a/org/openepics/names/docker/StructuresSystemGroupIT.java

...t/java/org/openepics/names/docker/StructuresSystemIT.java

src/test/java/org/openepics/names/util/ValidateUtilTest.java