Explore variations for image comment icons
The image comment icons used with the Design tab use a smaller instance of the comment icon within a circle, and this is to explore alternates that could:
* More prominently feature a comment graphic
* Better infer where a comment is getting placed
* Have a non-transparent center so that it overlays artwork
* Potentially be more of a 1:1 visually with the numbered comment marker
**Curent**


## Questions
1. What is the reason for having a light and dark version?
/cc @phikai @jareko
## Exploration
| | Light | Dark |
| ------ | ------ | ------ |
| A |  |  |
| B |  |  |
| C |  |  |
[Comment Marker CSS demo →](https://codepen.io/lostsatellites/pen/xxKvxmp)
## Checklist
- [ ] Update icon in GitLab SVGs
- [ ] Update icon sizing in GitLab. MR: https://gitlab.com/gitlab-org/gitlab-design/-/issues/660
issue