Improvements to suggested and archive URLs when editing a mapping [60838740]

* Archive and suggested URLs are secondary fields that rarely need to be filled in, move them behind a disclosure to avoid confusion
* Introduce text that explains the meaning of both URL types, with appropriate link text to disclose the fields
* Use cancel or remove to switch the view back and reset the field
* Default to showing the fields when they are present
* Switch labels for read only fields to a key-value definition list that simulates label styles
* Introduce a mappings helper to create national archive URLs
* When JS is disabled, show all form values and separate the form with visible legends, and hide JS interactions
* There is a known caveat that if the default host is wrong the national archive link may not work and that the fix isn’t clear to the user
* Cleanup some of the base styles to use more of the bootstrap defaults
* Change how we deal with the non-javascript case so we have hooks for JS enabled and disabled