ISBAT see the editor width change based on the selected page layout

[richtabor]

As a user, I should be able to see the proper width of my page as I switch away from the default page layout option.

AC:
When I select a custom layout, such as the fullwidth layout, the editor should have a class applied to the editor, which can then be used to style the width of the editor properly (using editor-frame.scss.

Screen recording:

[richtabor]

There is a layouts.js file, as well as styling within the editor-frame.scss stylesheet, but it does not currently function properly.

[richtabor]

Also, the selected layout's class should remain in the admin body classes when saved.

[aledesma-godaddy]

Closing issues and PRs in preparation for repository archival