[2pt] Add flag to optionally deleted intermediate inundation files

[RobHanna-NOAA]

In the mapping/{huc}/{lid} are a bump of inundated images changed extent files. It is done to each branch, then merged to a single "extent" file for that {huc}/{lid}/{lid}_{magnitude}_extent.tif. We obviously need to keep the final extent files per magnitude and not all of the branch intermediary files. Note: that system is now in but the code commented for version or two for tracing reasons. Maybe uncomment in the next HV 2.1.8 release (in a few months) to clean up all of those intermediate tif files as there is A LOT. Update: We have commented out code in there to delete them, just make it driven by an arg to delete or not (default delete). Can helps with debugging during dev.

Add an argument in for deleting or not, default to delete. Nice to have when code/debugging and most of the code is there, easy to finish.