Upgrade to Discord.js v13

[brandoningli]

Is your feature request related to a problem? Please describe.

Describe the solution you'd like

Update Discord.js to the new v13.

Describe alternatives you've considered

Leaving on v12 leaves features on the table.

Additional context

• Guide to upgrading from v12 to v13
• There will have to be a lot of extensive testing to make sure everything works with these major updates.
• We'll likely want to institute a code freeze for anything unrelated to compatibility while working on this.

[brandoningli]

Notes of things to look at during this cutover:

• [x] Switch to built-in support for Slash Commands
• [x] Embeds are now an array: channel.send({ content: 'Hello!', embeds: [embed, embed2] });
• [x] Fields that should be strings are now required to be strings. Use template strings here.
• [x] All intents must be explicitly passed
• [x] thingID becomes thingId
• [x] client.on("message") becomes client.on("messageCreate")
• [x] Make SpikeKit reply use the message.reply function. See the docs
• [x] Channel Types are now in line with Discord's naming conventions. See the docs
• [x] collection.array() becomes [...collection.values()] and collection.keyArray() becomes [...collection.keys()]
• [x] guild.member(user) becomes guild.members.cache.get(user.id)
• [x] member.hasPermission(perm) becomes member.permissions.has(perm)
• [x] member.lastMessage and related were removed
• [x] TextChannel.{start,stop}Typing is now just TextChannel.sendTyping() that stops after 10 seconds or when a message is sent.