HPCC-11062 Set Archived to true in the response of searching archived WU

Calling WUQuery + Type="archived workunits" returns a list of WUs. The
response "Archived" field for each WU should be set to 'true'.
Merge pull request #5570 from wangkx/h11062b

HPCC-11062 Set Archived to true in the response of searching archived WU

Reviewed-By: Richard Chapman <rchapman@hpccsystems.com>