Add a delete-after-import flag which will delete the .car file from filesystem after import is complete
This also needs to work even when --staging-dir is specified - in this case, we want it to manually delete the carfile from the original storage location in addition to deleting from the staging dir
delete-after-importflag which will delete the.carfile from filesystem after import is complete--staging-diris specified - in this case, we want it to manually delete the carfile from the original storage location in addition to deleting from the staging dir