Add report abuse button to epic actions

What does this MR do and why?

• Resolves https://gitlab.com/gitlab-org/modelops/anti-abuse/team-tasks/-/issues/429
• Adds Report abuse to administrator dropdown item in epic actions.

Screenshots or screen recordings

report-abuse-epic

How to set up and validate locally

1. Log-in as admin and navigate to any group, eg: http://127.0.0.1:3000/groups/gitlab-org/-/epics. Click on an epic.
2. Using the epic actions, click on Report abuse to administrator and complete the form.
3. Navigate to /admin/abuse_reports. You should see an abuse report. If you click on it, you will be able to see the content of the epic that you just reported and a link to go to the epic as well.

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.