Expand listener priorities

[SamB440]

Is your feature request related to a problem? Please describe. Packet listeners are currently limited by an enum: https://github.com/retrooper/packetevents/blob/2.0/api/src/main/java/com/github/retrooper/packetevents/event/PacketListenerPriority.java

When not shading and multiple plugins are using packetevents, this can become problematic, if two plugins listen on a priority then the order in which they execute is unknown, and plugins such as anticheats would like to be after any packet changes made by plugins.

Describe the solution you'd like The addition of priority integers instead of an enum.

Describe alternatives you've considered to solve your solution without us adding this as a feature? Shading to stay ahead of plugins using the packetevents plugin instance.

Additional context Add any other context or screenshots about the feature request here.