MC-21524: Schema introspection return incomplete results

- Added changes for the schema return

Author: avattam06

lib/internal/Magento/Framework/GraphQl/Query/Fields.php

@@ -49,7 +49,8 @@ public function setQuery($query, array $variables = null)
         } catch (\Exception $e) {
             // If a syntax error is encountered do not collect fields
         }
-        if (isset($queryFields['IntrospectionQuery'])) {
+        if (isset($queryFields['IntrospectionQuery']) || (isset($queryFields['__schema'])) ||
+            (isset($queryFields['__type']))) {
             // It must be possible to query any fields during introspection query
             $queryFields = [];
         }
@@ -60,7 +61,7 @@ public function setQuery($query, array $variables = null)
      * Get list of fields used in GraphQL query.
      *
      * This method is stateful and relies on the query being set with setQuery.
-     *
+     *-
      * @return string[]
      */
     public function getFieldsUsedInQuery()