Expose `keyPrefix` to `RateLimiterRes` if available
When we use multiple rate limiter together, and `consume()` fails and throw `RateLimiterRes`, we are unable to determine which rate limiter is failing. as the interface of `RateLimiterRes` is too generic.

If the `keyPrefix` is forwarded `RateLimiterRes`, we can then identify which rate limiter is failing.