feat(batch34): implement and verify group B cluster consumer features

dotnet/src/ZB.MOM.NatsNet.Server/Accounts/Account.JetStream.cs

@@ -614,4 +614,25 @@ public sealed partial class Account
 
         return js.CheckAccountLimits(selected.Limits, config, reservation);
     }
+
+    internal (JetStreamAccountLimits? Limits, string Tier, JsAccount? JsAccount, JsApiError? Error) SelectLimits(int replicas)
+    {
+        _mu.EnterReadLock();
+        try
+        {
+            var jsa = JetStream;
+            if (jsa == null)
+                return (null, string.Empty, null, JsApiErrors.NewJSNotEnabledForAccountError());
+
+            var (selected, tier, found) = jsa.SelectLimits(replicas);
+            if (!found)
+                return (null, string.Empty, jsa, JsApiErrors.NewJSNoLimitsError());
+
+            return (selected, tier, jsa, null);
+        }
+        finally
+        {
+            _mu.ExitReadLock();
+        }
+    }
 }