utils
Introduce `append_related_issues` function and `IssueRelated` enum to manage related issue linking. Update Gitea action to utilize the new functionality for appending related issues in work package content. Add corresponding tests.
Reviewed-on: #2 Co-authored-by: Julien Fastré <julien.fastre@champs-libres.coop> Co-committed-by: Julien Fastré <julien.fastre@champs-libres.coop>