Display number of unread items on desktop app icon

We should display the number of unread notifications on the Desktop App icon, the same as we've done with the iOS app. We need to also translate this to the Desktop App, for Windows, Mac, and also the Android app.

So if I have 4 missed calls, 4 chat and unread chats, or any number of notifications that I have unread, that same number should be displayed in the icon of the application on the Mac Dock, Windows System Tray, and Android app icon.