Add automatic command registration

[JstnMcBrd]

Resolves a TODO item. Reviewing commit-by-commit may be easier.

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This PR makes it so commands are automatically registered upon startup - no special entrypoint required. Along the way, I made several other improvements.

Efficient

• Commands are not registered unless they are already out-of-sync
• Pre-fetch guilds to avoid unnecessary network requests

More correct

• Deleting all local commands will remove all registered commands now (empty arrays were ignored before)
• Check more properties of commands (descriptions, type, nsfw, subcommand groups, subcommands, options, etc), not just names
• Adjusted terminology (deploy -> register)
• Added uptime worker test for clientReady (previously uncovered)

Simpler

• No more parseArgs
• No more package.json command scripts
• No more revokeCommands (never used in practice)
• Don't log exact differences between actual vs expected commands, just report whether in-sync
• Most of the complexity is now isolated to finding comparable values between local and registered commands, while the rest of the process is much simpler
• Simpler tests (for the most part)

Also added types to some commands - necessary because they are left undefined if not set, making them impossible to compare with registered values.