GraphQL: Optimize queries, fixes some null returns (on object), fix stitched GraphQLUpload (#6709)

* Optimize query, fixes some null returns, fix stitched GraphQLUpload

* Fix authData key selection

* Prefer Iso string since other GraphQL solutions use this format

* fix tests

Co-authored-by: Antonio Davi Macedo Coelho de Castro <adavimacedo@gmail.com>

src/GraphQL/loaders/defaultGraphQLTypes.js

@@ -15,7 +15,7 @@ import {
   GraphQLUnionType,
 } from 'graphql';
 import { toGlobalId } from 'graphql-relay';
-import { GraphQLUpload } from 'graphql-upload';
+import { GraphQLUpload } from '@graphql-tools/links';
 
 class TypeValidationError extends Error {
   constructor(value, type) {
@@ -162,7 +162,7 @@ const serializeDateIso = (value) => {
     return value;
   }
   if (value instanceof Date) {
-    return value.toUTCString();
+    return value.toISOString();
   }
 
   throw new TypeValidationError(value, 'Date');

src/GraphQL/loaders/filesMutations.js

@@ -1,6 +1,6 @@
 import { GraphQLNonNull } from 'graphql';
 import { mutationWithClientMutationId } from 'graphql-relay';
-import { GraphQLUpload } from 'graphql-upload';
+import { GraphQLUpload } from '@graphql-tools/links';
 import Parse from 'parse/node';
 import * as defaultGraphQLTypes from './defaultGraphQLTypes';
 import logger from '../../logger';
@@ -14,7 +14,7 @@ const handleUpload = async (upload, config) => {
       const chunks = [];
       stream
         .on('error', reject)
-        .on('data', chunk => chunks.push(chunk))
+        .on('data', (chunk) => chunks.push(chunk))
         .on('end', () => resolve(Buffer.concat(chunks)));
     });
   }
@@ -52,7 +52,7 @@ const handleUpload = async (upload, config) => {
   }
 };
 
-const load = parseGraphQLSchema => {
+const load = (parseGraphQLSchema) => {
   const createMutation = mutationWithClientMutationId({
     name: 'CreateFile',
     description: