Threaded notifications (#4644)

* implemented grouping

* implemented presenting the thread

* improved the implementation by reusing the presentation action

* add Thread group to DMs to differentiate from non threaded messages of the same DM

* name for a threaded notification in group room

* focus event when tapping on a notification

* pr suggestions

* document

ElementX/Sources/Other/Extensions/UNNotificationContent.swift

@@ -25,6 +25,10 @@ extension UNNotificationContent {
     @objc var pusherNotificationClientIdentifier: String? {
         userInfo[NotificationConstants.UserInfoKey.pusherNotificationClientIdentifier] as? String
     }
+    
+    @objc var threadRootEventID: String? {
+        userInfo[NotificationConstants.UserInfoKey.threadRootEventIdentifier] as? String
+    }
 }
 
 extension UNMutableNotificationContent {
@@ -55,6 +59,15 @@ extension UNMutableNotificationContent {
         }
     }
     
+    override var threadRootEventID: String? {
+        get {
+            userInfo[NotificationConstants.UserInfoKey.threadRootEventIdentifier] as? String
+        }
+        set {
+            userInfo[NotificationConstants.UserInfoKey.threadRootEventIdentifier] = newValue
+        }
+    }
+    
     var unreadCount: Int? {
         userInfo[NotificationConstants.UserInfoKey.unreadCount] as? Int
     }