Change config structure to allow nestest structures in config.json

[kuskoman]

Instead of haveing flat config allow to nest objects inside of it Example: current config:

{
   // [...]
  "lavalinkHost": "localhost",
  "lavalinkPassword": "",
  "lavalinkPort": "2333",
   // [...]
}

nested config:

{
   "lavalink": {
      "host": "localhost",
      "password": "",
      "port": "2333"
   }
}