task5(batch39): add reply parsing and consumer identity helpers

dotnet/src/ZB.MOM.NatsNet.Server/JetStream/NatsStream.Consumers.cs

@@ -227,6 +227,20 @@ internal sealed partial class NatsStream
         }
     }
 
+    internal Exception? DeleteConsumer(NatsConsumer consumer)
+    {
+        ArgumentNullException.ThrowIfNull(consumer);
+
+        lock (_consumersSync)
+        {
+            _consumers.Remove(consumer.Name);
+            _consumerList.RemoveAll(c => ReferenceEquals(c, consumer));
+        }
+
+        consumer.DeleteWithoutAdvisory();
+        return null;
+    }
+
     internal void SwapSigSubs(NatsConsumer consumer, string[]? newFilters)
     {
         _ = consumer;