UI: Add confirmation when clicking stop stream

I decided to add a confirmation message box simply to prevent cases
where users may accidentally click "Stop Streaming".

obs/data/locale/en-US.ini

@@ -224,6 +224,8 @@ Basic.Main.StartRecording="Start Recording"
 Basic.Main.StartStreaming="Start Streaming"
 Basic.Main.StopRecording="Stop Recording"
 Basic.Main.StopStreaming="Stop Streaming"
+Basic.Main.StopStreaming.Title="Stop stream?"
+Basic.Main.StopStreaming.Text="Are you sure you want to stop the stream?"
 
 # basic mode file menu
 Basic.MainMenu.File="&File"

obs/window-basic-main.cpp

@@ -3058,6 +3058,12 @@ void OBSBasic::StartStreaming()
 
 void OBSBasic::StopStreaming()
 {
+	QMessageBox::StandardButton button = QMessageBox::question(this,
+			QTStr("Basic.Main.StopStreaming.Title"),
+			QTStr("Basic.Main.StopStreaming.Text"));
+	if (button == QMessageBox::No)
+		return;
+
 	SaveProject();
 
 	if (outputHandler->StreamingActive())