feat: define StreamStore/ConsumerStore interfaces from Go store.go

Port IStreamStore, IConsumerStore, StoreMsg, StreamState, SimpleState,
ConsumerState, FileStoreConfig, StoreCipher, StoreCompression types.
Rename Models.StreamState → ApiStreamState to avoid namespace conflict.

src/NATS.Server/JetStream/Api/JetStreamApiResponse.cs

@@ -45,7 +45,7 @@ public sealed class JetStreamApiResponse
 public sealed class JetStreamStreamInfo
 {
     public required StreamConfig Config { get; init; }
-    public required StreamState State { get; init; }
+    public required ApiStreamState State { get; init; }
 }
 
 public sealed class JetStreamConsumerInfo