SSDM-1019 : V3 AS API - Fully cover all existing methods with automated tests

.../api/v3/executor/experiment/CreateExperimentExecutor.java

...generic/server/api/v3/executor/tag/CreateTagExecutor.java

...eneric/server/api/v3/executor/tag/GetTagNameExecutor.java

...eric/shared/dto/identifier/AbstractIdentifierFactory.java

...ic/server/api/v3/executor/tag/GetTagNameExecutorTest.java

...a/ch/ethz/sis/openbis/systemtest/api/v3/AbstractTest.java

...z/sis/openbis/systemtest/api/v3/CreateExperimentTest.java

...thz/sis/openbis/systemtest/api/v3/ListExperimentTest.java