Implement the empty weave::Bluetooth interface.

This is preparation for further bluetooth work.

Bug: 24009281
Change-Id: Ia9bafb04abf9e479950ad20aae224f4918861504
diff --git a/buffet/manager.h b/buffet/manager.h
index c4b7bb4..e8eb44d 100644
--- a/buffet/manager.h
+++ b/buffet/manager.h
@@ -30,6 +30,7 @@
 
 namespace buffet {
 
+class BluetoothClient;
 class BuffetConfig;
 class DBusCommandDispacher;
 class HttpTransportClient;
@@ -124,6 +125,7 @@
 
   class TaskRunner;
   std::unique_ptr<TaskRunner> task_runner_;
+  std::unique_ptr<BluetoothClient> bluetooth_client_;
   std::unique_ptr<HttpTransportClient> http_client_;
   std::unique_ptr<NetworkClient> network_client_;
   std::unique_ptr<MdnsClient> mdns_client_;