Display page content in the Static Site Editor

What does this MR do?

Displays the content of the page the user wants to edit in the Static Site Editor’s edit area. It displays a skeleton loader while the content is loading. This MR is part of a series of Merge Requests to deliver #212560 (closed). The other merge requests in this series are:

• Implement a service that fetches a page source content using GitLab API: !28598 (merged)
• Implement Vuex state management to load the page source content: !28481 (merged)

To test this work in your local environment, use the following integration MR: !28615 (closed)

See #212560 (closed) for more information. See the issue to obtain information about high-level design decisions and see user mockups.

Screenshots

This gif shows all the MRs working in conjunction:

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers
• Informed Infrastructure department of a default or new setting change, if applicable per definition of done