Add a gaming mode to the binary

[albertlarsan68]

Hello,

I would be happy to see a mode that allows to "play" the game, like 3b1b has show in his video.

It would give a first guess, then ask for the colors, repeating this until all the colors are green or more than 6 guesses have been given.

Asking the human the colors could be done in Correctness::compute(), instead of computing it from a known answer. Maybe using Option<&str> instead of &str for the answer, in order to select wether to ask to the console or solve internally ?