HPCC-11783 Return NodeGroup in WUInfo ECLResult

The WsWorkunits/WUInfo is updated to return 'NodeGroup'
inside the ECLResult when the result has a 'logicalName'.

Signed-off-by: wangkx <kevin.wang@lexisnexis.com>
There are various places including this, that construct this implicit hthor group name, it should also be common code, e.g. getHThorGroupName(<hthor-instance-name>)