CI: Test our *2john tools #5433
Description
We need to start automatic testing of our *2john tools, perhaps on GitHub Actions using inputs from our https://github.com/openwall/john-samples repo. Most of these tools are Python scripts and some have dependencies, so this task might not be completed in one step. It's OK to start with testing our C compiled programs, then proceed to add more.
Also, maybe some of this (not requiring large input files) should become part of our make check (and individual tests automatically skipped when dependencies are not satisfied? so that make check remains usable to test john itself everywhere it currently is).