Allow checking out just a single branch for huge repos

We have a huge repo, the checkout step takes a significant amount of time.
Please allow customizing the checkout behaviour, so we can choose to perform a checkout of a single git branch, and not the entire repo.

For example, when asking Claude to review a PR for a specific branch, it does not need any to have any other branches in the git repo.

Allowing this option would optimize the time it takes to checkout the repo and will speed up the process.