Global ratelimit sentinel value

[Bluenix2]

Currently it is impossible to distinguish between simply not receiving ratelimit headers and a particular route not having any specific ratelimit.

It would be cool if, with v10 (because it might be a breaking change), Discord started sending a sentinel value in X-RateLimit-Bucket or maybe using X-RateLimit-Scope to indicate what type of ratelimits a particular route is affected by. This would mean that client libraries knows whether ratelimit headers just wasn't received, or the route is only affected by the global ratelimit.

It's not clear from the documentation, whether Discord wants routes without received buckets to be handled as only limited by the global ratelimit - or the endpoint (method + path) be used as the fallback bucket.