[LMS-2104] basic support for virtual data sets in UI

...d/openbis/generic/server/CommonBusinessObjectFactory.java

...ch/systemsx/cisd/openbis/generic/server/CommonServer.java

...enbis/generic/server/authorization/PredicateExecutor.java

...temsx/cisd/openbis/generic/server/business/bo/DataBO.java

...sd/openbis/generic/server/business/bo/ExternalDataBO.java

...eric/server/business/bo/ICommonBusinessObjectFactory.java

...d/openbis/generic/server/business/bo/IExternalDataBO.java

...a/ch/systemsx/cisd/openbis/generic/shared/dto/DataPE.java

.../openbis/generic/shared/translator/DataSetTranslator.java

...eb/client/application/dataset/DataSetPropertiesPanel.java