feat(cli): add --primary-config, --backup-config, --failover-retry-count to data connection commands

Thread backup data connection fields through management command messages,
ManagementActor handlers, SiteService, site-side SQLite storage, and
deployment/replication actors. The old --configuration CLI flag is kept
as a hidden alias for backwards compatibility.

src/ScadaLink.SiteRuntime/Actors/DeploymentManagerActor.cs

@@ -630,7 +630,8 @@ public class DeploymentManagerActor : ReceiveActor, IWithTimers
                     foreach (var dc in command.DataConnections)
                     {
                         await _storage.StoreDataConnectionDefinitionAsync(
-                            dc.Name, dc.Protocol, dc.PrimaryConfigurationJson);
+                            dc.Name, dc.Protocol, dc.PrimaryConfigurationJson,
+                            dc.BackupConfigurationJson, dc.FailoverRetryCount);
                     }
                 }