Add attributes for RdfUriGenerator

Closes #3510908

src/Attribute/RdfUriGenerator.php

+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\rdf_sync\Attribute;
+
+use Drupal\Component\Plugin\Attribute\Plugin;
+use Drupal\Core\StringTranslation\TranslatableMarkup;
+
+/**
+ * Defines an RdfUriGenerator.
+ */
+#[\Attribute(\Attribute::TARGET_CLASS)]
+class RdfUriGenerator extends Plugin {
+
+  /**
+   * Constructs an RDF URI generator attribute.
+   *
+   * @param string $id
+   *   The plugin ID.
+   * @param \Drupal\Core\StringTranslation\TranslatableMarkup $label
+   *   The human-readable name of the widget type.
+   */
+  public function __construct(
+    public readonly string $id,
+    public readonly TranslatableMarkup $label,
+  ) {}
+
+}