<!--IssueSummary start--> <details> <summary> Everyone can contribute. [Help move this issue forward](https://handbook.gitlab.com/handbook/marketing/developer-relations/contributor-success/community-contributors-workflows/#contributor-links) while earning points, leveling up and collecting rewards. </summary> - [Work on this issue](https://contributors.gitlab.com/manage-issue?action=work&projectId=278964&issueIid=454799) - [Close this issue](https://contributors.gitlab.com/manage-issue?action=close&projectId=278964&issueIid=454799) </details> <!--IssueSummary end--> This issue is the first step in unifying issue saving behaviour between our third party importers. 1. Extract shared relation saving behaviour to a base class. 2. Create a reusable `IssueSaver` class which leverages this base class. 3. Update `Gitlab::BitbucketImport::Importers::IssueImporter` to use this new class.