Add Migrate module support

Some changes for #13 to make it work in Drupal 10: Plugin folder should be capitalized, Url.php also with capitals and namespace is needed. See zip attached with the full module, just enable, rollback the failing migration and reimport.

namespace Drupal\custom_url_migrate\Plugin\migrate\field;

use Drupal\migrate\Plugin\MigrationInterface;
use Drupal\migrate_drupal\Plugin\migrate\field\FieldPluginBase;

/**
 * Defines a URL field migration plugin.
 *
 * @MigrateField(
 *   id = "url",
 *   core = {7},
 *   type_map = {
 *     "url" = "link"
 *   },
 *   source_module = "url",
 *   destination_module = "link"
 * )
 */
class Url extends FieldPluginBase {

  /**
   * {@inheritdoc}
   */
  public function getFieldWidgetMap() {
    return [
      'url' => 'link',
    ];
  }

  /**
   * {@inheritdoc}
   */
  public function getFieldFormatterMap() {
    return [
      'default' => 'link',
      'url' => 'link',
      'url_external' => 'link',
    ];
  }

  /**
   * {@inheritdoc}
   */
  public function processFieldValues(MigrationInterface $migration, $field_name, $data) {
    $process = [
      'plugin' => 'sub_process',
      'source' => $field_name,
      'process' => [
        'uri' => 'value',
        'title' => 'title', // Assuming that the URL field may have an optional title
        'options' => 'options', // For any additional options that might be attached to the link
      ],
    ];
    $migration->setProcessOfProperty($field_name, $process);
  }

}