Wire up debug view: route subscribe/unsubscribe through DeploymentManagerActor

DeploymentManagerActor now handles SubscribeDebugViewRequest and
UnsubscribeDebugViewRequest by forwarding to the appropriate Instance Actor.
This completes the debug view data flow from Central UI through to the site's
Instance Actor snapshot. Reduced refresh interval to 2s for responsiveness.

src/ScadaLink.CentralUI/Components/Pages/Deployment/DebugView.razor

@@ -244,7 +244,7 @@
                 {
                     // Connection may have dropped
                 }
-            }, null, TimeSpan.FromSeconds(5), TimeSpan.FromSeconds(5));
+            }, null, TimeSpan.FromSeconds(2), TimeSpan.FromSeconds(2));
         }
         catch (Exception ex)
         {