Feature: Authentication Listener on App

[cmelchior]

In Realm Java and Realm Kotlin we expose an "Authentication Listener" on the App instance which makes it possible to listen to authentication changes like "LoggedIn", "LoggedOut" and "Removed" across all users.

We have implemented this in the SDK layer, but it would be nice to move it to ObjectStore for two reasons:

• It would make it easier for other SDK's to implement it.
• It would allow us to also be able to correctly report a "LoggedOut" event when the refresh token expires. Currently, this is not something we can track at the SDK layer, so we cannot report an event in this case.

[kiburtse]

Is there some input from other sdks which can directly benefit from this soon?

[cmelchior]

There are also feature requests from Dart here: #6497

[nirinchev]

This has also been requested by .NET. Currently we have notifications in Core that the user changes, but not what exactly changes.