Preemptively show that the service is stopping

More accurately describes the state of the service and more importantly unregisters the network callback which could have updates while we're trying to shut down

Author: t895

app/src/main/kotlin/dev/clombardo/dnsnet/vpn/AdVpnService.kt

@@ -506,6 +506,8 @@ class AdVpnService : VpnService(), Handler.Callback, AdVpnCallback {
     private fun stopVpn() {
         logi("Stopping Service")
 
+        updateVpnStatus(VpnStatus.STOPPING)
+
         vpnThread.stopThread()
 
         logger.save()