Notifications are now handled when the app is in a killed state (#801)

* WIP, added support for receiver id and managed a way to store the app router state

* WIP, added support for receiver id and managed a way to store the app router state

* Notification Manager is now becoming the UNUserNotificationDelegate ASAP

* code improvements + changelog

* fixed Unit Tests

* pr suggestions

ElementX/Sources/Other/Extensions/UNNotificationContent.swift

@@ -0,0 +1,35 @@
+//
+// Copyright 2023 New Vector Ltd
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+import Foundation
+import UserNotifications
+
+extension UNNotificationContent {
+    @objc var receiverID: String? {
+        userInfo[NotificationConstants.UserInfoKey.receiverIdentifier] as? String
+    }
+}
+
+extension UNMutableNotificationContent {
+    override var receiverID: String? {
+        get {
+            userInfo[NotificationConstants.UserInfoKey.receiverIdentifier] as? String
+        }
+        set {
+            userInfo[NotificationConstants.UserInfoKey.receiverIdentifier] = newValue
+        }
+    }
+}