Decap improvement: Add means to show variation code snippet without page chrome

[anselmbradford]

Hey it's a mega pain to develop and test things that depend on full page breakpoints in the existing design system layout with a sidebar, since when resizing the sidebar makes the content narrow but it's still wide enough to not trigger the breakpoint. What if under the "SHOW DETAILS" we had a button around/in the HTML snippet panel that opened a new tab with that HTML snippet in a bare bones HTML page so it can be viewed full-screen in isolation away from the design system chrome. Thoughts?

[sonnakim]

On hold till Decap migration

[anselmbradford]

https://github.com/cfpb/design-system/pull/1980 has been merged.