refactor filer_pb.Entry and filer.Entry to use GetChunks()

for later locking on reading chunks

weed/filer/abstract_sql/abstract_sql_store.go

@@ -158,7 +158,7 @@ func (store *AbstractSqlStore) InsertEntry(ctx context.Context, entry *filer.Ent
 		return fmt.Errorf("encode %s: %s", entry.FullPath, err)
 	}
 
-	if len(entry.Chunks) > filer.CountEntryChunksForGzip {
+	if len(entry.GetChunks()) > filer.CountEntryChunksForGzip {
 		meta = util.MaybeGzipData(meta)
 	}