Move email editor components out of the engine folder

MAILPOET-6215

packages/js/email-editor/src/editor-hooks.ts

@@ -0,0 +1,14 @@
+import { ComponentType } from 'react';
+
+import { MediaUpload } from '@wordpress/media-utils';
+import { addFilter } from '@wordpress/hooks';
+
+export const initHooks = (): void => {
+	// see https://github.com/WordPress/gutenberg/blob/master/packages/block-editor/src/components/media-upload/README.md
+	const replaceMediaUpload = (): ComponentType => MediaUpload;
+	addFilter(
+		'editor.MediaUpload',
+		'mailpoet/email-editor/replace-media-upload',
+		replaceMediaUpload
+	);
+};