This will users to change the wording of the most recent commit,
something they might want to do if they realize they made a small typo
of some kind or if the formatting of their commit message is wrong, but
don't have any other changes they need to make.

Release Notes:

- Commit messages can now be amended in the UI without any other changes
needing to be made.

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Co-authored-by: Cole Miller <cole@zed.dev>