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
This makes sure that the user will not get a PHP warning if theu are not running the latest version of varia that has that function.
Since varia doesn't have that feature enabled this PR removes the function as well.
Using a `+` instead of a space here will cause the font name to be doubly encoded (as `PT%2BSans`), resulting in an error 400 when loading from Google Fonts.
@josephscott kindly validated the fix by testing on his sandbox.
