Design exploration - Content Editor in comments

Problem to solve

We want the Content Editor to enable rich Markdown editing across GitLab. One area where a lot of Markdown gets written is in comments, whether that's on issues, epics, snippets, or MRs.

Proposal

Introduce a toggle between the raw Markdown editor currently available in notes/comments and the Content Editor. People should be able to toggle between the editors seamlessly without losing data.

Details

We could consider replacing the Preview tab with the Content Editor as it has matured to the point that it's giving a fairly accurate representation of the styled Markdown. But there are some differences, so this shouldn't be rolled out globally until we've validated that approach. '