[suggestion] Add support for CustomModelData Icons inside packinfo.yml

Summary

Add support inside packinfo.yml files in order tu setup Icons with CustomModelData attributes

Usage

Add a parameter called CustomModelData inside packinfo.yml in order to override the NBT data of MATERIAL used to display the Pack Icon.

Value

Developers users can create custom Icons for his packs to improve quality. Only admin users who has access to /mmmenu will notice this change.

Priority

Very low. Impact just for server-admin users with access to /mmmenu

Implementation

Add a new parameter inside packinfo.yml called CustomModelData, if it is defined use that number to create the ItemStack inside the menu. Else use NO CustomDataModel in the icon.