Optional constructor params to allow us to test
OptionaldefaultRootMessagingProviderFactory: MessagingProviderFactory<IRootMessagingProvider<RequestMessage>>This is used if there is no messagingProviderFactory passed in the createRoot method
OptionalrootMessagePublisherFactory: ((messagingProvider: IRootMessagingProvider<RequestMessage>, directory: AppDirectory, window: Window) => RootMessagePublisher)Creates a new instance of DesktopAgent
DesktopAgent
A factory to create an instance of DesktopAgent