private async void SaveCommand_Executed(object sender, ExecutedRoutedEventArgs e)
        {
            SaveFileDialog saveFileDialog = new SaveFileDialog
            {
                Filter = "Json Files (*.json)|*.json|Txt Files (*.txt)|*.txt"
            };

            if (saveFileDialog.ShowDialog() == true)
            {
                await JsonIOservice.WriteToJsonFileAsync(_contacts, saveFileDialog.FileName);
            }
        }