Use the official WP JS hooks library [MAILPOET-2081]

assets/js/src/hooks.js

@@ -0,0 +1,8 @@
+import { createHooks } from '@wordpress/hooks';
+
+// Make sure the hooks library is available globally
+// because it is used in views (e.g. newsletter/editor.html)
+window.wp = window.wp || {};
+window.wp.hooks = window.wp.hooks || createHooks();
+
+export default window.wp.hooks;