Deprecation for dialogClass

Closes #3296098

core/lib/Drupal/Core/Ajax/OpenDialogCommand.php

@@ -76,6 +76,16 @@ public function __construct($selector, string|\Stringable|null $title, $content,
     $title = PlainTextOutput::renderFromHtml($title);
 
     $dialog_options += ['title' => $title];
+    if (isset($dialog_options['dialogClass'])) {
+      @trigger_error('Passing $dialog_options[\'dialogClass\'] to OpenDialogCommand::__construct() is deprecated in drupal:10.3.0 and will be removed in drupal:12.0.0. Use $dialog_options[\'classes\'] instead. See https://www.drupal.org/node/3440844', E_USER_DEPRECATED);
+      if (isset($dialog_options['classes']['ui-dialog'])) {
+        $dialog_options['classes']['ui-dialog'] = $dialog_options['classes']['ui-dialog'] . ' ' . $dialog_options['dialogClass'];
+      }
+      else {
+        $dialog_options['classes']['ui-dialog'] = $dialog_options['dialogClass'];
+      }
+    }
+
     $this->selector = $selector;
     $this->content = $content;
     $this->dialogOptions = $dialog_options;