ENH Avoid use of 'new' keyword on injectable classes from this module.

It's not uncommon to want to override or enhance some functionality in vendor code that doesn't have extension points, so we should avoid the `new` keyword when instantiating injectable classes from the module.

code/Form/UserForm.php

@@ -118,7 +118,7 @@ class UserForm extends Form
      */
     public function getFormFields()
     {
-        $fields = new UserFormsFieldList();
+        $fields = UserFormsFieldList::create();
         $target = $fields;
 
         foreach ($this->controller->data()->Fields() as $field) {
@@ -174,7 +174,7 @@ class UserForm extends Form
             ->filter('Required', true)
             ->column('Name');
         $requiredNames = array_merge($requiredNames, $this->getEmailRecipientRequiredFields());
-        $required = new UserFormsRequiredFields($requiredNames);
+        $required = UserFormsRequiredFields::create($requiredNames);
         $this->extend('updateRequiredFields', $required);
         $required->setForm($this);
         return $required;