Add command permission checks

Level 0: Every user - Public commands
Level 1: Guild owners or members with respective admin role - Elevated guild commands
Level 2: Global admins - Every command including levels below

commands/ping.js

@@ -4,6 +4,7 @@ module.exports = {
     data: new SlashCommandBuilder()
             .setName("ping")
             .setDescription("Ping, yes"),
+    permissionLevel: 1,
     async execute(interaction) {
         interaction.reply({
             content: "Pong!",