[Upfront Builder] Add a global code element in the same manner as global CSS

Just as like adding scripts to the body of an HTML, I'd like to add code to all pages, a global code field is what I'd like to see implemented.
There's already a global CSS field at the moment, ad a tab for Js.
So that code then populates every page's footer, header, or...

ps: I know you can add a code element, but this is only per page template, not global.