added killSwitch switcher (#746)

* added killSwitch switcher
* KillSwitch toggle for OpenVPN and XRay
* killSwitch toggle for AWG/WG protocol
* Some fixes for killSwitch

client/ui/controllers/settingsController.h

@@ -63,6 +63,9 @@ public slots:
 
     bool isCameraPresent();
 
+    bool isKillSwitchEnabled();
+    void toggleKillSwitch(bool enable);
+
 signals:
     void primaryDnsChanged();
     void secondaryDnsChanged();