Assets: Build JS & CSS files

Also add RTL support for stylesheets and post preview.

Author: obenland

assets/js/activitypub-admin.js

@@ -1,4 +1,6 @@
-jQuery( function( $ ) {
+import jQuery from 'jquery';
+
+jQuery( function ( $ ) {
 	// Accordion handling in various areas.
 	$( '.activitypub-settings-accordion' ).on( 'click', '.activitypub-settings-accordion-trigger', function() {
 		var isExpanded = ( 'true' === $( this ).attr( 'aria-expanded' ) );

assets/js/activitypub-header-image.js

@@ -6,7 +6,7 @@
  * @see wp-admin/js/site-icon.js
  */
 
-/* global jQuery, wp */
+import jQuery from 'jquery';
 
 ( function ( $ ) {
 	var $chooseButton = $( '#activitypub-choose-from-library-button' ),