UI: Disable stream settings if streaming

UI/window-basic-settings-stream.cpp

 #include <QMessageBox>
 
 #include "window-basic-settings.hpp"
+#include "obs-frontend-api.h"
 #include "obs-app.hpp"
 #include "window-basic-main.hpp"
 #include "qt-wrappers.hpp"
@@ -105,6 +106,9 @@ void OBSBasicSettings::LoadStream1Settings()
 
 	UpdateKeyLink();
 
+	bool streamActive = obs_frontend_streaming_active();
+	ui->streamPage->setEnabled(!streamActive);
+
 	loading = false;
 }