Add co-author to commits
Add addCoAuthor command for commits
- Implement the `addCoAuthor` command to add co-authors to commits.
- Utilize suggestions helpers to populate author names from the suggestions list.
- Added command to gui at `LocalCommitsController`.
This commit introduces the `addCoAuthor` command, which allows users to easily add co-authors to their commits. The co-author names are populated from the suggestions list, minimizing the chances of user input errors. The co-authors are added using the Co-authored-by metadata format recognized by GitHub and GitLab.
