Add prepared_at to merge_request api to let people know when diffs ready
What does this MR do and why?
Expose the prepared_at attribute - this allows users to know when the preparation of a merge request is finished.
To Test:
- Load a MR (http://localhost:3000/api/v4/projects/1/merge_requests/1)
- Ensure
prepared_atis exposed
Related to #386562 (closed)
Edited by Marc Shaw