Initially intended as a part-fix for #3134 to enable child themes to swap typefaces that get included more easily, this also extends that change across to many themes using the common patterns.
It explicitly does not change the following themes:
Spearhead (uses different endpoint and method)
And the following themes that have multiple functions that generate typeface includes so as to avoid confusion:
* canard
* gazette
* illustratr
* publication
* Reorganize styles a bit, consolidate header styles, and delete empty selectors
* Update editor colour palette to match theme's colours
* Remove styles for pre and code blocks in editor; doesn't look identical to the front-end but they blocked the text from being edited
