Add FOSS push support

All is in the title, to investigate. See https://git.jami.net/savoirfairelinux/ring-client-android/issues/525

Also see https://gitlab.com/foss-push/planning/#foss-push-protocol-alternatives, and get in contact as there has been the mentioned prototype funding grant.

Matrix/Riot is discussing SSE (Server Sent Events) https://github.com/vector-im/riot-android/issues/3152

In fact this is what basically the proxy already does We open a direct TCP connection and we receive values from here.

Could SSE bring an advantage here? Compared to your solution and for the good of the battery?

SSE has 2 advantages:

1. Instead of multiple sockets, you only have one socket.
2. If multiple applications use SSE and it's a standard one, we can imagine to ask users to only add one application (aka SSE client) for all apps, this is basically what FCM on Android is.

closed

added typefeature request label