Node hiding for 'queryNodeIndex'.
Fix for 'visible' traversal.
Moved JoernTag-class to extra file to allow it to be syper-class of JoernHide.
joern-hide implemented and tested briefly.
Added 'unhide' feature. Hide and unhide can both process ids and directories now.
Make more lookup-functions 'visibility'-capable.
removed node-hiding steps because they have been moved to python-joern.