Update character inventory

[lee-aaron]

• Drops and stuff should be picked up by a character and be added to the correct inventory

This should be done after actor states are incorporated

For now, write to the database on pickup. However, this is not a scalable solution. It would be best to have another service continuously update characters inventory in the database every 5 min or so in batches (ie not every character is saved at absolute 5 min intervals; maybe 5 min intervals from login time).