Reimplement the submodules parser to not depend on the go-git dependency. See #8222 for the full refactor context. Reviewed-on: https://codeberg.org/forgejo/forgejo/pulls/8438 Reviewed-by: Gusted <gusted@noreply.codeberg.org> Co-authored-by: oliverpool <git@olivier.pfad.fr> Co-committed-by: oliverpool <git@olivier.pfad.fr>