Issue #3457990 by TR: [10.3] Convert TypedDataFormWidget plugins and discovery to attributes

Closes #3457990

src/Attribute/TypedDataFormWidget.php

+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\typed_data\Attribute;
+
+use Drupal\Component\Plugin\Attribute\Plugin;
+use Drupal\Core\StringTranslation\TranslatableMarkup;
+
+/**
+ * PHP Attribute class for typed data form widget plugins.
+ */
+#[\Attribute(\Attribute::TARGET_CLASS)]
+class TypedDataFormWidget extends Plugin {
+
+  /**
+   * Constructs a typed data form widget attribute object.
+   *
+   * @param string $id
+   *   The plugin ID. The machine-name of the widget.
+   * @param \Drupal\Core\StringTranslation\TranslatableMarkup|null $label
+   *   (optional) The human-readable name of the widget.
+   * @param \Drupal\Core\StringTranslation\TranslatableMarkup|null $description
+   *   (optional) A short description of the widget.
+   * @param class-string|null $deriver
+   *   (optional) The deriver class.
+   */
+  public function __construct(
+    public readonly string $id,
+    public readonly ?TranslatableMarkup $label = NULL,
+    public readonly ?TranslatableMarkup $description = NULL,
+    public readonly ?string $deriver = NULL,
+  ) {}
+
+}