Add WorkItemWidgetVulnerabilities with related vulnerabilities

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/183548



Merged-by: Lorenz van Herwaarden <lvanherwaarden@gitlab.com>
Approved-by: Gregory Havenga <11164960-ghavenga@users.noreply.gitlab.com>
Approved-by: Alexandru Croitor <acroitor@gitlab.com>
Reviewed-by: Alexandru Croitor <acroitor@gitlab.com>