Workaround for FPixelStreamingModule::StartupModule() setting invalid TargetWidow on Streamer

Thanx, Jacob!
I`l tried one more time and find solution. In this lines:

Streamer->SetTargetViewport(TargetViewport->GetViewportWidget());
Streamer->SetTargetWindow(TargetViewport->FindWindow());

we need change to

this->SetTargetViewport(TargetViewport->GetViewportWidget());
this->SetTargetWindow(TargetViewport->FindWindow());