Working on fields order in inheritance

When using some UIs like GraphiQL, field order can be relevant for the end user.
This PR changes field order so that fields from the most parent class are displayed before fields from child classes.

Author: moufmouf

src/Types/TypeAnnotatedObjectType.php

@@ -43,8 +43,11 @@ public static function createFromAnnotatedClass(string $typeName, string $classN
                     $fields = $fieldProvider->getSelfFields($className);
                 }
                 if ($parentType !== null) {
-                    // Note: with +=, the keys already present are not overloaded
-                    $fields += $parentType->getFields();
+                    $finalFields = $parentType->getFields();
+                    foreach ($fields as $name => $field) {
+                        $finalFields[$name] = $field;
+                    }
+                    return $finalFields;
                 }
                 return $fields;
             },