* When a block theme is active, add a notice to advise using Additional CSS in the Site Editor. A similar notice is already directing users to Custom CSS in the Customizer when a classic theme is active.
* When there is a minified file (`*.min.css`) present for the current CSS file, warn that any edits may not be served to visitors.
Developed in https://github.com/WordPress/wordpress-develop/pull/10279
Follow-up to [60934].
Props westonruter, peterwilsoncc, jorbin.
See #63012.
Built from https://develop.svn.wordpress.org/trunk@60943
git-svn-id: http://core.svn.wordpress.org/trunk@60279 1a063a9b-81f0-0310-95a4-ce76da25c4cd