HPCC-11657 Allow downloading of "File" as well as zip/gzip for WU helpers

Fixes HPCC-11657

Signed-off-by: Gordon Smith <gordon.smith@lexisnexis.com>
Merge pull request #6055 from GordonSmith/HPCC-11657

HPCC-11657 Allow downloading of "File" as well as zip/gzip for WU helpers

Reviewed-By: Miguel Vazquez <miguel.vazquez@lexisnexis.com>
Reviewed-By: Richard Chapman <rchapman@hpccsystems.com>