[Feature] GCM Support

[DoM1niC]

Google Cloud Messaging are include into the Client code, but we need a Plugin 4 Prosody, after this we have to reconfigure the Client 4 this Plugin.

https://github.com/atomarea/FlowX/tree/Main/src/push/java/net/atomarea/flowx/services

App Server
https://github.com/ToothlessGear/node-gcm
https://github.com/mattg888/GCM-PHP-Server-Push-Message

Prosody Plugin
https://modules.prosody.im/mod_cloud_notify.html