Allow user to tag comments directly in commentor

**Why ?**

Unlike in Github, updating a comment in gitlab does not fire the update webhook. The users using GitLab will need to be able to post tag their comments directly in commentor. Github users will also profit from it.

**What ?**
First, it would be helpful for users to see the comments that are not tagged thanks to this "Warning" icon.


Then we will need to add an edit functionality.

- [Easy solution] We could trigger the comment edition just by clicking on the body column.
- [Rich solution] We can also think of displaying a "Tag this comment" modal whenever the user clicks on the warning icon or on the comment body, this modal would display the user's tags and let him select the ones he wants to tag the comment with. This solution would probably be easier to implement bulk tagging afterward.

No file or test is named. Start by tracing the comment body column and the warning icon shown for untagged comments, then assess whether clicking either should open direct editing or a tag-selection modal. Done means users can identify untagged comments and tag or edit them directly in Commentor.

Written by the indexing model from the issue text.