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/cloud/cloudCodeModuleFile.js

@@ -0,0 +1,3 @@
+Parse.Cloud.define('cloudCodeInFile', () => {
+  return 'It is possible to define cloud code in a file.';
+});