Introduces flow types for storage (#4349)

* Introduces flow types for storage

* Better typing of QueryOptions

* Adds flow types to SchemaCOntroller,

- runs flow on pre tests
- fixes flow

* Adds ClassLevelPermissions type

* Moves Controller types into a single file

* Changes import styles

* Changes import styles

* fixing method setIndexesWithSchemaFormat (#4454)

Fixing invalid database code in method `setIndexesWithSchemaFormat`:

* It must be a transaction, not a task, as it executes multiple database changes
* It should contain the initial queries inside the transaction, providing the context, not outside it;
* Replaced the code with the ES6 Generator notation
* Removing the use of batch, as the value of the result promise is irrelevant, only success/failure that matters

* nits

* Fixes tests, improves flow typing

spec/helper.js

@@ -27,10 +27,10 @@ var cache = require('../src/cache').default;
 var ParseServer = require('../src/index').ParseServer;
 var path = require('path');
 var TestUtils = require('../src/TestUtils');
-var MongoStorageAdapter = require('../src/Adapters/Storage/Mongo/MongoStorageAdapter');
 const GridStoreAdapter = require('../src/Adapters/Files/GridStoreAdapter').GridStoreAdapter;
 const FSAdapter = require('@parse/fs-files-adapter');
-const PostgresStorageAdapter = require('../src/Adapters/Storage/Postgres/PostgresStorageAdapter');
+import PostgresStorageAdapter from '../src/Adapters/Storage/Postgres/PostgresStorageAdapter';
+import MongoStorageAdapter from '../src/Adapters/Storage/Mongo/MongoStorageAdapter';
 const RedisCacheAdapter = require('../src/Adapters/Cache/RedisCacheAdapter').default;
 
 const mongoURI = 'mongodb://localhost:27017/parseServerMongoAdapterTestDatabase';