Support Confluence Layouts in article pages

As a site manager, I want to make use of the 'layouts' option in the Confluence editor, so I can better control the visual impact of the content in my Viewport articles.

Acceptance criteria:

• All layouts show in Viewport articles, except for the Three columns with sidebars option

• The Three columns with sidebars option defaults to the Three columns option to ensure readability in the help center theme

• Normal width, wide and full-width options in Confluence are transformed into the same content width

• On Mobile, all layouts default to a single column to ensure readability