Add support for AsyncChatEvent in Paper server

[Mowstyl]

Information

This PR fixes #5243.

Details

Proposed fix:

Since the EssentialsDiscord plugin only listens to AsyncPlayerChatEvent, which is called before calling AsyncChatEvent, any changes made to the message in the latter event will be ignored by the plugin. In order to fix it, I've added some classes to the PaperProvider and a new async event which will be called each time an AsyncChatEvent is received. The plugin checks if the AsyncChatEvent exists and registers the two listeners needed instead of the bukkit one.

Environments tested:

OS: Ubuntu 24.04 LTS

Java version: Oracle GraalVM 21.0.3+7.1

• [x] Most recent Paper version (1.XX.Y, git-Paper-BUILD)
• [ ] CraftBukkit/Spigot/Paper 1.12.2
• [ ] CraftBukkit 1.8.8

Demonstration: