HPCC-10588 Improve File Spray Multi Selection

Fixes HPCC-10588

Signed-off-by: Gordon Smith <gordon.smith@lexisnexis.com>
Merge pull request #5303 from GordonSmith/HPCC-10588

HPCC-10588 Improve File Spray Multi Selection

Reviewed-By: Miguel Vazquez <miguel.vazquez@lexisnexis.com>
Reviewed-By: Richard Chapman <rchapman@hpccsystems.com>