HPCC-11127 Fix getXmlResult handling of supplied values

Also update provided xml values when roxie runs a workunit query and
common up code with eclagent.

Signed-off-by: Anthony Fishbeck <anthony.fishbeck@lexisnexis.com>
Merge pull request #5849 from afishbeck/viewvariables11127

HPCC-11127 Fix getXmlResult handling of supplied values

Reviewed-By: Gavin Halliday <gavin.halliday@lexisnexis.com>
Reviewed-By: Richard Chapman <rchapman@hpccsystems.com>