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
To avoid duplicating this file across all FSE themes
I'm moving it to the FSE plugin instead and providing
hooking to theme activation there. This is now viable
since we are no longer hardcoding the templates in
themes, but fetching them from the Dotcom API.
This adds required functionality to support rendering FSE header and
footer on all site pages (static and dynamic). It's also includes the
data population functionality, which has now been removed from the plugin
and will be delegated to each theme for maximum flexibility.
