enable distributed rate limiter in pingora limit

[github2023spring]

What is the problem your feature solves, or the need it fulfills?

distributed rate limiter with pingora limit, so that we can deploy pingora in a group of hosts to handle larger amount of traffics.

Describe the solution you'd like

maybe, an async trait that can invoke external service, like redis

[MMADUs]

there is the storage trait that you can implement for caching, and make your own caching strategy

[johnhurt]

This is a great idea, but it isn't something we are likely to add to pingora. That sort of cross-process coordination isn't a goal for the core library. If there was a distributed rate limiter (or just an agreement on how to use some distributed storage to store rates), it could be called within pingora just like the existing rate-limit constructs.