Blocks: Add unit test coverage for Patterns registry.

Prior to this changeset, we did not seem to have any unit test coverage for the Patterns registry (`WP_Block_Patterns_Registry`).

With Block Hooks logic recently added ([56649]), it is particularly advisable to add some unit tests to the `get_registered()` and `get_all_registered()` methods to guard hooked block insertion against regressions.

Fixes #59476.
Built from https://develop.svn.wordpress.org/trunk@56733


git-svn-id: http://core.svn.wordpress.org/trunk@56245 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/version.php

@@ -16,7 +16,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '6.4-beta1-56732';
+$wp_version = '6.4-beta1-56733';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.