* Allow configuration of start point.
* Use git switch --create.
* Maybe fix string type.
* Fix wrong flag.
* Add --dry_run flag.
* Not sure if this is needed.
* Dry run should be safe even with uncommitted changes.
* Remove side effects with --dry_run.
* Checkpoint progress.
* Make `dry_run` parameter optional so tests pass.
* Implement suggestions from code review.
* Checkpoint progress.
* Remove new dry_run_pr_number option.
* Rename --start_point to --branch_start_point.