feat(android,ios): play from Downloads, and say what a download waits for

- A finished download row on the phones plays when tapped and has an
  Open button for its title, as the desktop's does.
- iOS queued downloads say "Waiting for Wi-Fi" or "Waiting for a
  connection", as Android's already do.
- Android download workers post their notifications as one group, each
  named for its episode, under a "Downloading 12 episodes" summary.
  Before, a season made fourteen loose notifications that all said
  "Making episode available offline".

ios/ProtonStream/App/ProtonStreamApp.swift

@@ -185,7 +185,10 @@ struct RootView: View {
             // on a form that has done its job.
             SharesView(incomingLink: $incomingLink, onFirstShareAdded: { select(.library) })
         case .downloads:
-            DownloadsView()
+            DownloadsView(onPlay: play, onOpen: { title in
+                destination = .library
+                selectedTitleKey = title.key
+            })
         case .settings:
             SettingsView()
         }