fix ktest to use JCommander

The last of the refactorings to remove Apache Commons CLI.

@osa1 please review.
I'm a bit confused about this part. We're using Jansi to handle output stream's color support. Do we still need to pass redirection info to color class?

Also, this doesn't work in general. Currently we're using `--output-file` argument but what happens if output is redirected using pipes etc. ? Jansi handles that too.