message: [storage] Add proptest roundtrip for InternalNode
  This test seems to have been lacking, add it in terms of the
  new serialize / deserialize functionality.
  Closes:
  Approved by: zamsden
diff: @@ -89,6 +89,13 @@ proptest! {
  serialize_u64_varint(input, &mut vec);
  assert_eq!(deserialize_u64_varint(&mut Cursor::new(vec)).unwrap(), input);
  }
  +
  + #[test]
  + fn test_internal_node_roundtrip(input in any::<InternalNode>()) {
  + let mut vec = vec![];
  + input.serialize(&mut vec).unwrap();
  + assert_eq!(InternalNode::deserialize(&vec).unwrap(), input);
  + }
  }
  #[test]
  