Issue #3423503: Allow to select recipients

Closes #3423503

src/Annotation/MessageRecipients.php

+<?php
+
+declare(strict_types = 1);
+
+namespace Drupal\message_plus\Annotation;
+
+use Drupal\Component\Annotation\Plugin;
+
+/**
+ * Defines message_recipients annotation object.
+ *
+ * @Annotation
+ */
+final class MessageRecipients extends Plugin {
+
+  /**
+   * The plugin ID.
+   */
+  public readonly string $id;
+
+  /**
+   * The human-readable name of the plugin.
+   *
+   * @ingroup plugin_translatable
+   */
+  public readonly string $title;
+
+  /**
+   * The description of the plugin.
+   *
+   * @ingroup plugin_translatable
+   */
+  public readonly string $description;
+
+}