Issue #3386762: Open field settings form in a modal in the field creation flow

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

+<?php
+
+namespace Drupal\Core\Ajax;
+
+/**
+ * Provides an AJAX command for opening a modal with URL.
+ */
+class OpenModalDialogWithUrl implements CommandInterface {
+
+  /**
+   * Constructs a OpenModalWithUrl object.
+   *
+   * @param string $url
+   *   The URL of the page.
+   * @param array $settings
+   *   The dialog settings.
+   */
+  public function __construct(
+    protected string $url,
+    protected array $settings
+  ) {}
+
+  /**
+   * {@inheritdoc}
+   */
+  public function render() {
+    return [
+      'command' => 'openDialogWithUrl',
+      'url' => $this->url,
+      'dialogOptions' => $this->settings,
+    ];
+  }
+
+}