feat: staff mod restrictions

[Collin-M]

This is my first Engine PR. Requesting feedback!

• Block staffmod 2+ from being attacked/attacking players
• Block staffmod 2 from trading/dueling
• Block staffmod 2 from adding items to party chest
• Dropped items from staffmod 2 never appear on the floor.
• Items sold/bought from shared inventories (shops) does not affect the stock of that inventory
• Staffmod 2+ items will not appear on the ground after a death.
• Remove random events from staffmod 2+ accounts
• No idle kick for staffmod 2+ accounts
• Vis 2 on login for staffmod 2+ accounts
• Prevent staffmod 2 from picking up items that don't belong to them