R1:e9f4a84a892c

Allow inline comments to be individually hidden

Summary:
Ref T7447. Implements per-viewer comment hiding. Once a comment is obsolete or uninteresting, you can hide it completely.

This is sticky per-user.

My hope is that this will strike a better balance between concerns than some of the other approaches (conservative porting, summarization, hide-all).

Specifically, this adds a new action here:

{F435621}

Clicking it completely collapses the comment into a small icon on the previous line, and saves the…