Allow setting syntax theme for generate step

[torbsto]

rich defaults to monokai as a syntax theme. This makes it unpleasant to read when using light color themes:

The syntax theme can be modified by passing a valid pygments theme when creating the syntax object.

[disrupted]

I am leaning more towards using the special ANSI themes. This way the user's terminal colors are used for the syntax highlighting. Could you try how this looks for you?

[torbsto]

But what would you choose - ansi_light or ansi_dark? I think ultimately it's the same problem. Also, it seems like it doesn't work for my setup. They both produce the same output and don't use any colors except for strings.

I've written a wrapper to pipe the output of kpops generate to bat -l yaml, so this issue could be closed from my side.