[Design] - Explore master-detail pattern for content in merge request
## Summary
This is only a design exploration at this time. Not planned yet for development.
This is example of the Pipelines. By using the master-detail pattern, users could view the information without loading a new page.
| Initial | Collapsed |
| ------ | ------ |
| {width=800 height=600} | {width=800 height=600} |
A past exploration of Commits as this presentation that could be used a a similar reference https://gitlab.com/gitlab-org/gitlab/-/issues/439830#note_1772141420
issue