Updated composite element pre render

Introduction of WebformCompositeFormElementTrait includes a new pre render for class WebformCompositeBase. New custom webform composite classes which require using a pre render method, should use the new method preRenderWebformCompositeFormElement.

Existing webform composite classes which use the original pre render method preRenderCompositeFormElement, may not function as expected and instead should convert to calling the new method.

Example from:

public static function preRenderCompositeFormElement($element) {
    $element = parent::preRenderCompositeFormElement($element);
    .
    .
   return $element;
}

Convert to:

public static function preRenderWebformCompositeFormElement($element) {
    $element = parent::preRenderWebformCompositeFormElement($element);
    .
    .
   return $element;
}

Where existing classes do not directly extend the WebformCompositeBase, add the new trait using:

use Drupal\webform\Element\WebformCompositeFormElementTrait;