Adjust sidebar when read/unread changes

[chris13524]

After reading notifications and switching to another subscription, the unread count and/or status does not change in the sidebar.

The sidebar should update when switching apps, but better would be to update upon each read event. Also if we so unread count instead of just a dot, the count should go up when new notifications are received.

[linear]

W3I-61 Adjust sidebar when read/unread changes