register all cron jobs in entrypoint (#12791)

closes https://github.com/twentyhq/core-team-issues/issues/1113

Three things I am not sure about - 
- Should we have a variable just like DISABLE_DB_MIGRATIONS to control
cron job registration behavior, i.e., DISABLE_CRON_JOBS_REGISTRATION?
- The location of the command ie, folder placement
- https://github.com/twentyhq/twenty/pull/12791/files#r2161734131

packages/twenty-server/src/modules/messaging/message-import-manager/messaging-import-manager.module.ts

@@ -83,6 +83,11 @@ import { MessagingMonitoringModule } from 'src/modules/messaging/monitoring/mess
     MessagingCursorService,
     MessagingSendMessageService,
   ],
-  exports: [MessagingSendMessageService],
+  exports: [
+    MessagingSendMessageService,
+    MessagingMessageListFetchCronCommand,
+    MessagingMessagesImportCronCommand,
+    MessagingOngoingStaleCronCommand,
+  ],
 })
 export class MessagingImportManagerModule {}