Fixed Unified API Bug in Working Version References

Fixed a bug in the Unified API when retrieving references to other content items for the working version of some content. Before the fix, methods Version#getReferences() , Version#getReferencesMap() , and Version#getReferences(CapPropertyDescriptor) could return outdated data for the special so-called "working version" (compare Version#isWorkingVersion).

(CMS-21881)