Splits auto-refreshing of MR widget into 2 requests:
- the one which uses etag-caching and invalidates the fields on change
- the one without caching
The idea is to gradually move all the fields to etag-cached endpoint
This commits extracts /merge_requests/1.json?serializer=widget
Into a separate /merge_requests/1/widget.json endpoint
This will allow to use caching for this request
When a project uses fast-forward merging strategy user has
to rebase MRs to target branch before it can be merged.
Now user can do rebase in UI by clicking 'Rebase' button
instead of doing rebase locally.
This feature was already present in EE, this is only backport
of the feature to CE. Couple of changes:
* removed rebase license check
* renamed migration (changed timestamp)
Closes#40301