feat: implement jetstream governance runtime parity semantics

src/NATS.Server/JetStream/StreamManager.cs

@@ -34,6 +34,7 @@ public sealed class StreamManager
     }
 
     public IReadOnlyCollection<string> StreamNames => _streams.Keys.ToArray();
+    public MetaGroupState? GetMetaState() => _metaGroup?.GetState();
 
     public IReadOnlyList<string> ListNames()
         => [.. _streams.Keys.OrderBy(x => x, StringComparer.Ordinal)];