Add notification when connection to the "Cloud Messaging" server is lost

I use microG "Cloud Messaging" to receive messages in messengers, and I have blocked the apps themselves from running in the background. As a result, receiving notifications fully depends on microG (or on opening the app). Please add a notification from microG when the connection to the server is lost. This will let users know that there may currently be issues with background delivery of messages.

The issue does not name files, tests, or entry points. Start by locating the Cloud Messaging connection lifecycle and existing notification handling, then determine how a lost server connection is detected. Done means microG notifies the user when that connection is lost so background message delivery problems are visible.

Written by the indexing model from the issue text.