Please don't "bury" PR comments just because the relevant lines have changed and they are "outdated"

Original description:

(Related to STASH-3263; my concern is slightly different; for internal reference see SSP-9230)

The comments in a PR diff disappear (Stash marks them as "outdated") when a new commit has been added to the source branch, and the line in question has been edited.

This is a neat feature in some ways, but it makes it nearly impossible to audit whether particular a comment has actually been addressed. Sometimes a changed line doesn't actually fix the relevant comment.

We have just been doing code reviews with HUNDREDS of minor comments, and a lot of them are gone unless I wade through the hundreds of comments in the activity stream to see if they are addressed.

I think the common issue between this and STASH-3263 is that comments need to be "attached" somehow to a specific immutable item in Stash, so as changes occur, the comments do not disappear, and can be found again.

How they are best presented in the context of a pull request, where the subject of a pull request is changing dynamically, is I guess the point of STASH-3263. If implemented, that would probably serve this purpose (though it seems rather complex, and having to wait for that to be fully implemented is kind of a downside).

There needs to be a way to browse all outstanding comments, even if they are "outdated", to make sure they were addressed. I found that I could get to them via the PR Activity stream on the overview page, but with hundreds of comments it is very difficult to manage, and there's no way to unambiguously refer to one comment in question if it is "outdated"; you have to wade through the hundreds of comments first until you get to the one you are looking for.

A coworker and I just wasted about an hour of time each, essentially re-doing the review for a couple of files, because of this problem.