Redesign page settings page
### Problem to solve
As part of the [Experience Baselines and Recommendations](https://about.gitlab.com/handbook/engineering/ux/experience-baseline-recommendations/) initiative, it was demonstrated the pages settings layout could use some improvement. Problems to solve:
* Reduce the visual impact of remove pages section
* Better connection between `New domain` and the domain list
* Reduce confusion of the `Save` button
* Provide an area for in UI documentation
### Intended users
Users with projects that use any static website generator or plain HTML that wish to leverage GitLab pages.
### Proposal
New page layout to address the above issues.
### Links / references
[Experience Baselines and Recommendations](https://about.gitlab.com/handbook/engineering/ux/experience-baseline-recommendations/)
[Experience Baselines and Recommendation: Release Q2](https://gitlab.com/groups/gitlab-org/-/epics/1326)
issue