Added MiniMessage support

You now need to use MiniMessage to make colored display names.
The old color system is no longer supported ("&a", "&3" ..).
Resources about how MiniMessage works:
https://docs.adventure.kyori.net/minimessage/format.html
https://webui.adventure.kyori.net/

Server and player commands

The subcommand "/npc command <npc name> <command>" has been replaced by two new subcommands:

• /npc serverCommand <npc name> <command>
• /npc playerCommand <npc name> <command>

The serverCommand will be executed by the console (as if you typed a command in the console). You can also include the {player} placeholder there.
Example: /npc serverCommand testNpc say Hello, {player}!
If I now interact with the testNpc, it will show "[Server] Hello, OliverHD!".

The playerCommand will be executed by the player (as if the player executed the command).
Example: /npc playerCommand testNpc warp pvp
If I now interact with the testNpc, I will get teleported to the pvp warp.