Fix some miscellaneous weirdness around push notifications

For some reason, I *stopped* the timer if we get a push message - which
makes *no* sense. It meant that NeoChat kept running in the background
for basically no reason.

We can also make the NotificationsManager::postPushNotification function
static and avoid creating some singletons.

(cherry picked from commit 94ea1305b2)

src/app/controller.cpp

@@ -318,8 +318,7 @@ void Controller::listenForNotifications()
     connect(timer, &QTimer::timeout, qGuiApp, &QGuiApplication::quit);
 
     connect(connector, &KUnifiedPush::Connector::messageReceived, [timer](const QByteArray &data) {
-        instance().m_notificationsManager.postPushNotification(data);
-        timer->stop();
+        NotificationsManager::postPushNotification(data);
     });
 
     // Wait five seconds to see if we received any messages or this happened to be an erroneous activation.

src/app/notificationsmanager.cpp

@@ -389,7 +389,7 @@ void NotificationsManager::postPushNotification(const QByteArray &message)
 
 #ifdef HAVE_KIO
         auto openAction = notification->addAction(i18n("Open NeoChat"));
-        connect(openAction, &KNotificationAction::activated, this, [=]() {
+        connect(openAction, &KNotificationAction::activated, notification, [=]() {
             QString properId = roomId;
             properId = properId.replace(u"#"_s, QString());
             properId = properId.replace(u"!"_s, QString());
@@ -403,8 +403,6 @@ void NotificationsManager::postPushNotification(const QByteArray &message)
         connect(notification, &KNotification::closed, qGuiApp, &QGuiApplication::quit);
 
         notification->sendEvent();
-
-        m_notifications.insert(roomId, {json["ts"_L1].toVariant().toLongLong(), notification});
     } else {
         qWarning() << "Skipping unsupported push notification" << type;
     }

src/app/notificationsmanager.h

@@ -53,7 +53,7 @@ public:
     /**
      * @brief Display a native notification for the given push notification.
      */
-    void postPushNotification(const QByteArray &message);
+    static void postPushNotification(const QByteArray &message);
 
     /**
      * @brief Handle the notifications for the given connection.