fix: Add redis config option for Bull & BullMQ

[adamlogic]

Previously we only offered redis_url as a way to specify a Redis connection, but that's not always enough. We now support a redis option that can either be an instance of IORedis or a configuration object. Essentially it follows the same API as the connection option in BullMQ:

new Judoscale({
  redis: redisOptions,
})

// or...

new Judoscale({
  redis: redisInstance,
})