UI: Add ability for stingers to use filters

This adds a menu item in the transitions config menu to access
filters for stinger transitions.

UI/window-basic-main-transitions.cpp

@@ -657,6 +657,7 @@ void OBSBasic::on_transitionProps_clicked()
 		return;
 
 	auto properties = [&]() { CreatePropertiesWindow(source); };
+	auto filters = [&]() { CreateFiltersWindow(source); };
 
 	QMenu menu(this);
 
@@ -674,6 +675,13 @@ void OBSBasic::on_transitionProps_clicked()
 	connect(action, &QAction::triggered, properties);
 	menu.addAction(action);
 
+	if (strcmp(obs_source_get_unversioned_id(source),
+		   "obs_stinger_transition") == 0) {
+		action = new QAction(QTStr("Filters"), &menu);
+		connect(action, &QAction::triggered, filters);
+		menu.addAction(action);
+	}
+
 	menu.exec(QCursor::pos());
 }