Add prefix comment on note when promoted to timeline event

What does this MR do and why?

Relates to #372994 (comment 1093890323)

Implements design - https://gitlab.com/gitlab-org/gitlab/uploads/4ecfd7956c245e8db3a5960fb1085f9e/Timeline_tab_-_v3.png

Screenshots or screen recordings

Screen_Recording_2022-09-09_at_2.52.16_PM

How to set up and validate locally

This is an extension fix for being able to promote a note into a timeline event.

So we can follow steps mentioned in !95934 (merged) for verification.

The only difference, you will be able to see the username and the comment being linked to the original note.

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

Related to #372994 (closed)