cvrptw_to_json: create output file in the same directory as input
cvrptw_to_json: create output file in the same directory as input

In order to re-use existing CVRP/compare_to_BKS.py script in CVRPTW
benchmarks use the same name convention as CVRPLIB converter - create
output file in the same place as input file + replace extension rather
than append it.

VROOM-Project/vroom-scripts,VROOM-Project/vroom-scripts