Add API to read Logistic Sections of item-with-entity-data

[robot256]

When vehicles with logistics enabled are mined into an item-with-entity-data in an inventory, their logistic request groups are stored somewhere. When the item-with-entity-data is used to build the vehicle again, the logistic request groups are restored. However, there is no method on LuaItem to read the stored logistic request group information.

I would like the ability to read the logistic section request data stored in the vehicle item so that it can be copied into e.g. a ghost entity matching the characteristic of the entity stored in the item.

Thank you for reading.