Port the notification backend to KNotifications

src/notificationsmanager.h

@@ -0,0 +1,21 @@
+#pragma once
+
+#include <QImage>
+#include <QMap>
+#include <QObject>
+#include <QString>
+
+#include <KNotification>
+
+class NotificationsManager : public QObject
+{
+    Q_OBJECT
+    
+public:
+    NotificationsManager(QObject *parent = nullptr);
+
+    Q_INVOKABLE void postNotification(const QString &roomId, const QString &eventId, const QString &roomName, const QString &senderName, const QString &text, const QImage &icon);
+
+private:
+    QMultiMap<QString, KNotification *> m_notifications;
+};