Use microG's Google Play Services library replacement to support Push Notifications for F-Droid users

[rugk]

Is your feature request related to a problem? Please describe.

F-Droid users cannot get "real" push notifications.

Describe the solution you'd like

MicroG is developing a replacement library for Play Services client library: https://github.com/microg/android_external_GmsLib https://github.com/microg/GmsCore (edit: changed URL)

It's FLOSS so it would AFAIK be allowed to be included in the F-Droid build. And if the F-Droid users do have the original Google Play Services or microG installed, they could use a real FLOSS app, but also get push notifications. (so stuff like #922 is not needed)

Describe alternatives you've considered

Leave it as it is; or remove Google Play Push services entirely. Both not ideal.

Additional context

It seems to be still in development, but it's an idea, at least.

[nextcloud-android-bot]

GitMate.io thinks possibly related issues are #2971 (Library upgrades), #15 (Two character password in Google Play screenshot), #3148 (Use Lombok), #1202 (Use avatars), and #922 (Remove google.gms play-services dependency).

[tobiasKaminsky]

Thank you for pointing this out!
Unfortunately the project is missing FCM (firebase cloud messaging) which is the successor of GCM (which is included).
There is already a ticket: https://github.com/microg/android_external_GmsLib/issues/14

I'll check this periodically and once there is progress, I'll try to include it in our app.

[mario]

Google is slowly open sourcing all the Firebase-* things, so I expect messaging to follow soon so there will be no need for client-side microg.

[tobiasKaminsky]

The referenced repo is archived, this is the new one: https://github.com/microg/GmsCore