Adding OG File Name Variable for Output CSV

** SQLECmd version **
1.0.0.0

**Is your feature request related to a problem? Please describe.**
Processing multiple similar formatted files that use the same Map cause indistinguishable resulting CSVs.

**Describe the solution you'd like**
When running with seek across Maps, would be great to have a potential variable to the "BaseFileName" field that would add the original file name that is processed to the final CSV filename.

**Describe alternatives you've considered**
N/A

**Additional context**
See screenshot below, the original DB files on the right and the resulting files on the left. I have to manually open each CSV to figure out which correlates to which original DB.


Start by locating the BaseFileName handling and the output path used when seeking across Maps. Trace how the original database filename is available during processing and verify that completed CSV names distinguish the source files without changing other output behavior.

Written by the indexing model from the issue text.