Hide outdated comments in review mode

[GuillaumeLagrange]

Issue Description

Type: feature request

Describe what happened (or what feature you want)

When reviewing PRs, especially after a few rounds, some files often get flooded by outdated comments, making it hard to distinguish comments that are still relevant

Describe what you expected to happen

In my opinion, if a comment is outdated, it does not beling in the review diff view anymore, which is more or less aligned with what github does in its diff view.

Since we already list outdated comments

How to reproduce it (as minimally and precisely as possible)

1. Open a PR with outdated comments
2. Start/resume a review
3. Open a file with outdated comments in the review diff view

Anything else we need to know?

I have a naive local implementation which I am happy with in #600, but I am not sure of the effects. I am completely unsure about the side effects, I know that it has made reviewing stuff much easier for my workflow