feat: Asynchronous initialization of Parse Server (#8232)

BREAKING CHANGE: This release introduces the asynchronous initialization of Parse Server to prevent mounting Parse Server before being ready to receive request; it changes how Parse Server is imported, initialized and started; it also removes the callback `serverStartComplete`; see the [Parse Server 6 migration guide](https://github.com/parse-community/parse-server/blob/alpha/6.0.0.md) for more details (#8232)

spec/DefinedSchemas.spec.js

@@ -631,7 +631,7 @@ describe('DefinedSchemas', () => {
     const logger = require('../lib/logger').logger;
     spyOn(DefinedSchemas.prototype, 'wait').and.resolveTo();
     spyOn(logger, 'error').and.callThrough();
-    spyOn(Parse.Schema, 'all').and.callFake(() => {
+    spyOn(DefinedSchemas.prototype, 'createDeleteSession').and.callFake(() => {
       throw error;
     });