HPCC-9732 WUQueryWidget ignores "Cluster=" params

Issue in TargetSelectWidget.js and default values.
Refactored to simply derive from dijit.form.Select.
Commoned up SampleSelectWidget into TargetSelectWidget.

Fixes HPCC-9732

Signed-off-by: Gordon Smith <gordon.smith@lexisnexis.com>
Merge pull request #4683 from GordonSmith/HPCC-9732

HPCC-9732 WUQueryWidget ignores "Cluster=" params

Reviewed-By: Miguel Vazquez <miguel.vazquez@lexisnexis.com>
Reviewed-By: Richard Chapman <rchapman@hpccsystems.com>