UI: Move "Check For Updates" menu to app menu on macOS

For apps using sparkle, it's normal for the "Check For Updates" button
to be in the app menu instead of the help menu, so let's put it there.

UI/window-basic-main.cpp

@@ -354,6 +354,7 @@ OBSBasic::OBSBasic(QWidget *parent)
 	ui->actionRemoveSource->setShortcuts({Qt::Key_Backspace});
 	ui->actionRemoveScene->setShortcuts({Qt::Key_Backspace});
 
+	ui->actionCheckForUpdates->setMenuRole(QAction::AboutQtRole);
 	ui->action_Settings->setMenuRole(QAction::PreferencesRole);
 	ui->actionE_xit->setMenuRole(QAction::QuitRole);
 #else