[#1333] services/control: Return pilorama info in ListShards RPC

Do not return backend type from the service for now, because memory
backend is expected to vanish.

Signed-off-by: Evgenii Stratonikov <evgeniy@nspcc.ru>

pkg/local_object_storage/pilorama/interface.go

@@ -36,6 +36,8 @@ type Forest interface {
 }
 
 type ForestStorage interface {
+	// DumpInfo returns information about the pilorama.
+	DumpInfo() Info
 	Init() error
 	Open() error
 	Close() error