refactor(command): ♻️ refactor how mcData is loaded

`mcData` is now directly put on bot and loaded once.
It can be accessed from anywhere `bot` is accessible.

lib/plugins/command.js

@@ -1,5 +1,5 @@
 const v = require('vec3')
-let mcData = require('minecraft-data')
+let mcData
 
 let cfg = {}
 let bot = {}
@@ -547,13 +547,12 @@ const load = (config) => {
     cfg = config
     bot = cfg.bot
 
-    mcData = mcData(bot.version)
+    mcData = bot.mcData || (bot.mcData = require('minecraft-data')(bot.version))
     for (const [key, fn] of Object.entries(events)) {
         events_registered.push(
             bot.on(key, fn)
         )
     }
-    mcData = require('minecraft-data')(bot.version)
 }
 
 const unload = () => {