feat: support different git repo (gitlab, gerrit)

[larrycai]

gitai init <repo type>

Default is for GitHub/PR, gitlab is MR,gerrit is review..

May based on different repo type to have different git workflow

[keli-wen]

Your proposal is excellent. I'm currently thinking of first implementing a split function. Submitting all messages as a single message is a bit too generic. How about trying to have the AI split them into multiple messages?