Introduce Expand All to make Accordion info visible

[garretthyder]

Feature request/bug description

Coming from core#46731 I wanted to raise the feature request of an 'Expand All' button to display all of the accordion contents from the site info screen.

This would enable users to get a quick overview of their information, as well as enable easier abilities to print or screenshot all of the information.

In many cases admins will use a screen or print of the contents over the copy to produce reports for their superiors. Enabling an expand all allows them to quickly capture this information in an aesthetic manner.

Screenshots

Concept - https://core.trac.wordpress.org/attachment/ticket/46731/Screen%20Shot%202019-03-30%20at%2012.42.26%20AM.png