'resolved all discussions' on MR hides too much detail

Problem to solve

A few projects on freedesktop.org have moved from mail or Bugzilla-based review workflows to GitLab MRs. So far it's been great, so thankyou!

When individual discussions are resolved, it notes that the discussion was resolved, and has a \/ Toggle discussion dropdown to show further details of that discussion.

When all discussions are resolved in one go, the chronology notes that 'all discussions' were resolved, without any details. It would be great for visibility to show which discussions were resolved at that point.

Further details

We are using the same rebasing-branch workflow from GNOME as documented in gitlab-ce#43566, to achieve a clean linear history without squashing, i.e. recipe form.

Currently we use standard MR discussions: when changes are required, we start a MR discussion. I submitted a MR to a project I am a core developer of, which was reviewed by another core developer. In each discussion, we arrived at an understanding of what needed to be done, I made the required changes, updated the MR with a new sequence of commits, and marked the discussion as done.

I am currently on v6 of that particular patchset (very soon to be v7), so there are a number of discussions which are purely historical and not relevant. The other developer reviewing has pointed out that it is difficult for him to track the discussions: the chronology notes that I 'resolved all discussions', but doesn't show exactly which discussions were resolved.

Though we want to trust submitters to do the right thing, it is very helpful for reviewers to be able to trace the exact changes made. To this end, it would be great if the 'resolved all discussions' chronology note was similar to 'pushed new commits', having either a dropdown or another way to show the exact discussions which were resolved in that point, so the reviewer can refresh their memory and compare the new changes to the new commits and code.

Proposal

'resolved all discussions' note in the MR chronology/activity view shows the exact set of discussions which were resolved at that point, linking to them or otherwise allowing them to be expanded.

What does success look like, and how can we measure that?

Reviewers can clearly and concisely see the set of discussions which were resolved between two revisions of an MR, regardless of whether all discussions were resolved at the same time, or just a subset.

Links / references

gitlab-ce#51336 from @danvet is related in that it more clearly shows the differences between two versions of the same MR. It comes from a project who are very early into using MRs, but I believe they are also interested in this bug.

@eliran.mesika @victorwu This is for freedesktop.org projects transitioning to GitLab MRs.