fix nested transaction crash on setting notification identifier

Session/Notifications/AppNotifications.swift

@@ -221,9 +221,7 @@ public class NotificationPresenter: NSObject, NotificationsProtocol {
             AppNotificationUserInfoKey.threadId: threadId
         ]
         
-        let transaction = transaction as! YapDatabaseReadWriteTransaction
-        let identifier: String = UUID().uuidString
-        incomingMessage.setNotificationIdentifier(identifier, transaction: transaction)
+        let identifier: String = incomingMessage.notificationIdentifier ?? UUID().uuidString
 
         DispatchQueue.main.async {
             notificationBody = MentionUtilities.highlightMentions(in: notificationBody!, threadID: thread.uniqueId!)

SessionMessagingKit/Sending & Receiving/MessageReceiver+Handling.swift

@@ -305,6 +305,7 @@ extension MessageReceiver {
         // Notify the user if needed
         guard (isMainAppAndActive || isBackgroundPoll), let tsIncomingMessage = TSMessage.fetch(uniqueId: tsMessageID, transaction: transaction) as? TSIncomingMessage,
             let thread = TSThread.fetch(uniqueId: threadID, transaction: transaction) else { return tsMessageID }
+        tsIncomingMessage.setNotificationIdentifier(UUID().uuidString, transaction: transaction)
         DispatchQueue.main.async {
             Storage.read { transaction in
                 SSKEnvironment.shared.notificationsManager!.notifyUser(for: tsIncomingMessage, in: thread, transaction: transaction)