Improve open action handling for notifications

Push notifications were not opened reliably. To improve robustness, the
following changes were introduced:
1. The notification opening logic was updated to become more similar to
   URL handling, in a way that uses better defined interfaces and
   functions that provide better result guarantees, by separating
   complex handling logic, and the side-effects/mutations that
   are made after computing the open action — instead of relying on a
   complex logic function that produces side-effects as a result, which
   obfuscates the actual behavior of the function.
2. The LoadableThreadView was expanded and renamed to
   LoadableNostrEventView, to reflect that it can also handle non-thread
   nostr events, such as DMs, which is a necessity for handling push
   notifications.
3. A new type of Notify object, the `QueueableNotify` was introduced, to
   address issues where the listener/handler is not instantiated at the
   time the app notifies that there is a push notification to be opened.
   This was implemented using async streams, which simplifies the usage
   of this down to a simple "for-in" loop.

Closes: https://github.com/damus-io/damus/issues/2825
Changelog-Fixed: Fixed issue where some push notifications would not open in the app and leave users confused
Signed-off-by: Daniel D’Aquino <daniel@daquino.me>

damus/damusApp.swift

@@ -86,11 +86,14 @@ class AppDelegate: NSObject, UIApplicationDelegate, UNUserNotificationCenterDele
     }
 
     func userNotificationCenter(_ center: UNUserNotificationCenter, didReceive response: UNNotificationResponse, withCompletionHandler completionHandler: @escaping () -> Void) {
+        Log.info("App delegate is handling a push notification", for: .push_notifications)
         let userInfo = response.notification.request.content.userInfo
         guard let notification = LossyLocalNotification.from_user_info(user_info: userInfo) else {
+            Log.error("App delegate could not decode notification information", for: .push_notifications)
             return
         }
-        notify(.local_notification(notification))
+        Log.info("App delegate notifying the app about the received push notification", for: .push_notifications)
+        Task { await QueueableNotify<LossyLocalNotification>.shared.add(item: notification) }
         completionHandler()
     }
 }