Add point of interest discussions to designs
* **<abbr title="Backend">BE</abbr> weight:** 3
* **<abbr title="Frontend">FE</abbr> weight:** 5
### Problem to solve
When engineers and designers are working together to build products, the issue is the single source of truth for knowing what needs to be built but it is difficult to provide feedback on designs because there may be multiple items of feedback for different areas of each screen or workflow, and it is hard to leave this feedback in the linear discussion thread on the issue.
It would be very helpful to be able to leave point of interest comments on images so that more detailed discussions can occur in more organized fashion.
### Target audience
Software Engineers, UX Designers and Product Managers all collaborate and give feedback on designs.
### Further details
Early iteration of https://gitlab.com/groups/gitlab-org/-/epics/660 after https://gitlab.com/gitlab-org/gitlab-ce/issues/56549 has been complete.
### Proposal
Working as designer, software engineer, or product manager, I will be able to:
- start a point of interest discussions on a screen in a version of a design
- reply to a point of interest discussion
- resolve a point of interest discussion
| **Mockup:** Designs on an issue | **Mockup:** Point of interest comments |
|---|---|
|  |  |
### What does success look like, and how can we measure that?
<!--- Define both the success metrics and acceptance criteria. Note thet success metrics indicate the desired business outcomes, while acceptance criteria indicate when the solution is working correctly. If there is no way to measure success, link to an issue that will implement a way to measure this -->
### Links / references
issue