Add commit type

[alsonick]

Added the option to allow users to prefix their commit messages with a commit type.

[Nutlope]

@alsonick Thanks for the PR! Wanted to add support for conventional commits so this is great but I have two thoughts:

1. Should we have GPT-3 infer the type by prompting it, then give users the option to correct it?
2. I don't want to mandate that everyone goes through this step, so it would have to be behind a flag. So folks would have to run something like aicommits --conventional-commits to pull this up

[AntoineKM]

It's a pity because in this case we have to choose a prefix while GTP-3 knows Conventional Commit V1

[rek]

Agree, it would be cool to ask OpenAI for the commit type