Add extra context argument for commands loaded through files

[itsMapleLeaf]

This argument would be passed in from the constructor:

// bot-context.ts
type BotContext = {
  message: string
}

// main.ts
await Gatekeeper.create<BotContext>({
  client,
  commandFolder: join(dirname(fileURLToPath(import.meta.url)), "commands"),
  context: { message: "hi" },
})

// commands/message.ts
export default function addCommands(
  gatekeeper: Gatekeeper,
  { message }: BotContext,
) {
  gatekeeper.addCommand({
    name: "message",
    description: "sends a message",
    async run(context) {
      context.reply(message)
    },
  })
}

This would allow passing values around through commands without having to use globals