Implement null scheme feature

smp-angular/src/app/app-config/smp-config.model.ts

...etails-dialog/service-group-details-dialog.component.html

...-details-dialog/service-group-details-dialog.component.ts

smp-api/src/main/java/eu/europa/ec/smp/api/Identifiers.java

...i/src/test/java/eu/europa/ec/smp/api/IdentifiersTest.java

smp-docker/compose/tomcat-mysql-smp-sml/docker-compose.yml

...eu/europa/ec/edelivery/smp/config/DatabaseProperties.java

...c/edelivery/smp/conversion/CaseSensitivityNormalizer.java

...pa/ec/edelivery/smp/conversion/ServiceGroupConverter.java

...ec/edelivery/smp/conversion/ServiceMetadataConverter.java

...a/ec/edelivery/smp/conversion/SmlIdentifierConverter.java

.../eu/europa/ec/edelivery/smp/data/dao/ServiceGroupDao.java

...n/java/eu/europa/ec/edelivery/smp/data/model/DBAlert.java

...eu/europa/ec/edelivery/smp/data/model/DBServiceGroup.java

...opa/ec/edelivery/smp/data/model/DBServiceGroupDomain.java

.../java/eu/europa/ec/edelivery/smp/data/ui/SmpConfigRO.java

...uropa/ec/edelivery/smp/data/ui/enums/SMPPropertyEnum.java

...uropa/ec/edelivery/smp/services/ConfigurationService.java

...elivery/smp/conversion/CaseSensitivityNormalizerTest.java

.../edelivery/smp/conversion/SmlIdentifierConverterTest.java