Block Directory: Convert it to UI Plugin to avoid bundling into Core (WordPress#17576)

* Block Directory: Convert it to UI Plugin to avoid bundling into Core

* Load the block directory assets only when the experiment is enabled

* Try to reimplement asset overrides to give more flexibility

* Add code style improvemements and perform code cleanup

* Try to make PHP unit tests pass by removing group check

* Ensure that packages and vendor scripts are printed in the footer

* Fix the has action check for the block directory assets

* Move gutenberg-block-directory experiment check out of the action

* Fix bin/get-vendor-scripts.php

Author: gziolo

bin/get-vendor-scripts.php

@@ -32,4 +32,13 @@ function wp_add_inline_script() {}
 
 require_once dirname( dirname( __FILE__ ) ) . '/lib/client-assets.php';
 
-gutenberg_register_vendor_scripts();
+/**
+ * Hi, phpcs
+ */
+function run_gutenberg_register_vendor_scripts() {
+	global $wp_scripts;
+
+	gutenberg_register_vendor_scripts( $wp_scripts );
+}
+
+run_gutenberg_register_vendor_scripts();

lib/block-directory.php

@@ -0,0 +1,21 @@
+<?php
+/**
+ * Block directory functions.
+ *
+ * @package gutenberg
+ */
+
+if (
+	gutenberg_is_experiment_enabled( 'gutenberg-block-directory' ) &&
+	! has_action( 'admin_enqueue_scripts', 'enqueue_block_editor_assets_block_directory' )
+) {
+	/**
+	 * Function responsible for enqueuing the assets required
+	 * for the block directory functionality in the editor.
+	 */
+	function gutenberg_enqueue_block_editor_assets_block_directory() {
+		wp_enqueue_script( 'wp-block-directory' );
+		wp_enqueue_style( 'wp-block-directory' );
+	}
+	add_action( 'enqueue_block_editor_assets', 'gutenberg_enqueue_block_editor_assets_block_directory' );
+}