Implementation of dynamic items

[iDimaBR]

This PR introduces support for dynamic items and automatic inventory updates in FastInv. Inventories can now refresh themselves at a defined interval, allowing real-time displays without needing to reopen or manually update the menu.

Benefits:

• Ideal for stats, timers, counters, or any live information.
• Simple to use while keeping compatibility with existing FastInv methods.
• Reduces the need for separate scheduled tasks for each inventory or manual work for do this.