[LMS-2104] database changes for Virtual Datasets

...systemsx/cisd/openbis/generic/shared/dto/ColumnNames.java

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

openbis/source/sql/generic/071/schema-071.sql

...bis/source/sql/postgresql/migration/migration-070-071.sql

openbis/sourceTest/sql/postgresql/071/007=data.tsv

...urceTest/sql/postgresql/071/017=database_version_logs.tsv

openbis/sourceTest/sql/postgresql/071/finish-071.sql

openbis/sourceTest/sql/postgresql/071/schema-071.sql