Consider switching to gitstatus for faster prompt

[brodock]

A ZSH theme https://github.com/romkatv/powerlevel10k implemented a clever way to make it super fast, instead of relying on existing git command, it uses a specific binary designed to be as fast as possible doing only the things that the prompt need.

The integration is currently done as a ZSH script: https://github.com/romkatv/powerlevel10k/tree/master/gitstatus

[bobthecow]

bobthefish has fairly optimized git integration, but i'm not opposed to making it even faster. i don't have a ton of time to look into it, but i'd welcome a pull request :)