handle dimension

assets/gooditem.fbs

@@ -1,5 +1,11 @@
 namespace internal.encoding.fbs;
 
+struct Dimensions {
+  width:float;
+  height:float;
+  length:float;
+}
+
 table GoodItem {
   sku:string;
   photo:string;
@@ -14,6 +20,7 @@ table GoodItem {
   tariff:float;
   cart:long;
   stock:short;
+  sizes:Dimensions;
   parameters:string;
   created_at:long;
 }