Adds support for PushScheduling (#3722)

* Add support for push scheduling

Add a configuration flag on the server to handle the availability of
push scheduling.

* Update push controller to skip sending only if scheduling is configured

Only skip push sending if scheduling is configured

* Update bad conventions

* Add CLI definitions for push scheduling

* Adds tests for pushTime

* Adds test for scheduling

* nits

* Test for not scheduled

src/ParseServer.js

@@ -95,6 +95,7 @@ class ParseServer {
     analyticsAdapter,
     filesAdapter,
     push,
+    scheduledPush = false,
     loggerAdapter,
     jsonLogs = defaults.jsonLogs,
     logsFolder = defaults.logsFolder,
@@ -182,6 +183,7 @@ class ParseServer {
     const pushController = new PushController();
 
     const hasPushSupport = pushAdapter && push;
+    const hasPushScheduledSupport = pushAdapter && push && scheduledPush;
 
     const {
       disablePushWorker
@@ -259,7 +261,8 @@ class ParseServer {
       userSensitiveFields,
       pushWorker,
       pushControllerQueue,
-      hasPushSupport
+      hasPushSupport,
+      hasPushScheduledSupport
     });
 
     Config.validate(AppCache.get(appId));