Changeset 57539 for trunk/tests/phpunit/tests/fonts/font-library/wpFontUtils/sanitizeFontFamily.php

Editor: Introduce the Font Library post types and low level APIs.

This is the first step towards adding the font library to WordPress.
This commit includes the font library and font face CPTs.
It also adds the necessary APIs and classes to register and manipulate font collections.

This PR backports the font library post types and low level APIs to Core. This is the first step to include the font library entirely into Core. Once this merged, we'll open a PR with the necessary REST API controllers.

Props youknowriad, get_dave, grantmkin, swissspidy, hellofromtonya, mukesh27, mcsf.
See #59166.