Allow user to collapse image within issue/MR discussion
<!--IssueSummary start--> <details> <summary> Everyone can contribute. [Help move this issue forward](https://handbook.gitlab.com/handbook/marketing/developer-relations/contributor-success/community-contributors-workflows/#contributor-links) while earning points, leveling up and collecting rewards. </summary> - [Close this issue](https://contributors.gitlab.com/manage-issue?action=close&projectId=278964&issueIid=20791) </details> <!--IssueSummary end--> When images are huge, it would be great to have the ability to collapse them like we already have collapsing of files in MRs. It could be similar to Slack: ![collapse](/uploads/8fa5dbd0b3855ba179c4511158e92a86/collapse.gif) Or we could allow the collapse of an entire note in a discussion
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