feat(llc, persistence): add support for open and close persistence via client.

Signed-off-by: xsahil03x <[email protected]>

packages/stream_chat_persistence/lib/src/stream_chat_persistence_client.dart

@@ -82,6 +82,9 @@ class StreamChatPersistenceClient extends ChatPersistenceClient {
   @override
   bool get isConnected => db != null;
 
+  @override
+  String? get userId => db?.userId;
+
   @override
   Future<void> connect(
     String userId, {