Point users to turn-off auto-sync when offline

[saberraz]

If Auto-Sync is on and there is no network connection, the app keeps showing this pop-up every time a change is made:

It would be good to point user to turn off the auto-sync and turn it on again when there is a network coverage, instead of showing this prompt on each change.

[wonder-sk]

It would be actually better to detect whether the network is reachable and do not even try to push. Qt should have functionality for the network detection now (using OS functionality):
https://doc.qt.io/qt-6/qnetworkinformation.html#reachability-prop

Then we would just need to signal somehow (change the sync icon?) that we're offline and there are changes to push