- Truncate branch names based on the width of the picker
- Use a footer for "Create branch" instead of a picker entry

Still to do:

- [x] Select the footer button when no matches and run the create logic
on `enter`
- [x] Make it possible to quickly select the footer button from the
keyboard when there are matches

Release Notes:

- Git Beta: Removed limitation that made it impossible to create a
branch from the branch picker when it too closely resembled an existing
branch name