jj-cz: conventional commits for jujutsu #9658

The lack of compatibility with commitizen bothered me, so I created jj-cz to fill this gap.

I’ve been using it for a few months already, and with the recent addition of the --new flag, I felt like today was a good day to finally share it.

The repository is here, in case you want to have a look at it.

Constructive criticism and suggestions are most welcome!