Add diffs type to commit on graphql

Closes gitlab-com/account-management/eastern-north-america/red-hat/red-hat-kernel-team#116

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/113259



Merged-by: Fabio Pitino <fpitino@gitlab.com>
Approved-by: Hitesh Raghuvanshi <hraghuvanshi@gitlab.com>
Approved-by: Fabio Pitino <fpitino@gitlab.com>
Reviewed-by: Fabio Pitino <fpitino@gitlab.com>
Reviewed-by: Patrick Bajao <ebajao@gitlab.com>
Reviewed-by: Aleksei Lipniagov <alipniagov@gitlab.com>
Reviewed-by: Lucas Zampieri <lzampier@redhat.com>
Reviewed-by: Hitesh Raghuvanshi <hraghuvanshi@gitlab.com>
Co-authored-by: Lucas Zampieri <lzampier@redhat.com>