Changeset 46111 for trunk/src/wp-includes/class-wp-block-styles-registry.php

Block Editor: Backport block styles server functions from block editor.

This commit backports the block styles functionality added to the block editor in ​https://github.com/WordPress/gutenberg/pull/16356.

Props: youknowriad, aduth, swissspidy.
Fixes #48039.