HPCC-9934 Add SprayFixed Input

Add new format selection for Spray Fixed Input. Add it to the existing
spray field under the Source area.

Signed-off by: Miguel Vazquez <miguel.vazquez@lexisnexis.com>
Merge pull request #4984 from miguelvazq/HPCC-9934

HPCC-9934 Add SprayFixed Input

Reviewed-By: Kevin Wang <kevin.wang@lexisnexis.com>
Reviewed-By: Richard Chapman <rchapman@hpccsystems.com>