[ENHANCEMENT] add debug clause to config JSON, but disable by default

[roycewilliams]

Reasoning: if you add the debug clause to the config JSON, but disable it by default, it will be much easier for new users to enable it. Especially when JSON doesn't allow the last trailing comma. :D

[roycewilliams]

Still very interested in this - it will reduce support burden on the development time by reducing troubleshooting friction. Also, one of the main benefits of this enhancement is to make it easier for end users to determine the exact hashcat command that is failing, so they can try it manually and observe the error. So a complementary way to attack the problem would be to more directly and immediately expose the exact command line used, and the error, when errors occur - at the default verbosity level (without having to enable debugging)