Represents a service, that provides functionality to manage the application life-cycle.
 /// <summary>
 /// Initializes a new <see cref="MainWindowViewModel"/> instance.
 /// </summary>
 /// <param name="applicationService">The application service, which can be used to manage the application lifecycle.</param>
 public MainWindowViewModel(ApplicationService applicationService)
 {
     this.applicationService = applicationService;
 }
 /// <summary>
 /// Initializes a new <see cref="DialogService"/> instance.
 /// </summary>
 /// <param name="applicationService">A service, which can be used to manage the application life-cycle.</param>
 public DialogService(ApplicationService applicationService)
 {
     this.applicationService = applicationService;
 }