service/tray: mostly complete StatusNotifierItem implementation

Notably missing dbusmenu which makes it actually useful.

src/services/status_notifier/host.hpp

@@ -0,0 +1,49 @@
+#pragma once
+
+#include <qcontainerfwd.h>
+#include <qdbusservicewatcher.h>
+#include <qhash.h>
+#include <qlist.h>
+#include <qloggingcategory.h>
+#include <qobject.h>
+#include <qtmetamacros.h>
+
+#include "dbus_watcher_interface.h"
+#include "item.hpp"
+
+Q_DECLARE_LOGGING_CATEGORY(logStatusNotifierHost);
+
+namespace qs::service::sni {
+
+class StatusNotifierHost: public QObject {
+	Q_OBJECT;
+
+public:
+	explicit StatusNotifierHost(QObject* parent = nullptr);
+
+	void connectToWatcher();
+	[[nodiscard]] QList<StatusNotifierItem*> items() const;
+	[[nodiscard]] StatusNotifierItem* itemByService(const QString& service) const;
+
+	static StatusNotifierHost* instance();
+
+signals:
+	void itemRegistered(StatusNotifierItem* item);
+	void itemReady(StatusNotifierItem* item);
+	void itemUnregistered(StatusNotifierItem* item);
+
+private slots:
+	void onWatcherRegistered();
+	void onWatcherUnregistered();
+	void onItemRegistered(const QString& item);
+	void onItemUnregistered(const QString& item);
+	void onItemReady();
+
+private:
+	QString hostId;
+	QDBusServiceWatcher serviceWatcher;
+	DBusStatusNotifierWatcher* watcher = nullptr;
+	QHash<QString, StatusNotifierItem*> mItems;
+};
+
+} // namespace qs::service::sni