Add Quick Settings tile (#660)

* Add Quick Settings tile

- Add multi-client support to AmneziaVpnService
- Make AmneziaActivity permanently connected to AmneziaVpnService while it is running
- Refactor processing of connection state changes on qt side
- Add VpnState DataStore
- Add check if AmneziaVpnService is running

* Add tile reset when the server is removed from the application

client/settings.h

@@ -191,6 +191,8 @@ public:
 
 signals:
     void saveLogsChanged(bool enabled);
+    void serverRemoved(int serverIndex);
+    void settingsCleared();
 
 private:
     QVariant value(const QString &key, const QVariant &defaultValue = QVariant()) const;