Currently we store the full item stack potentially with NBT data, caps and whatever else as part of the cable bus.

This is mostly unnecessary as we only need to item id to lookup the actual Item to test it for an IPartItem as this provides the factory to make the actual ItemStack.

The actual part can persist their own state through usual writeToNBT/readFromNBT and writeToStream/readFromStream when necessary.

This might need some further evalution in case the part needs an initial config based on the used ItemStack