Adds a no-op implementation of the rate-limit handler and exposes
it on the consul.Server struct.
It allows us to start working on the net/rpc and gRPC interceptors
and config (re)loading logic, without having to implement the full
handler up-front.
Co-authored-by: John Murret <john.murret@hashicorp.com>
Co-authored-by: Dhia Ayachi <dhia@hashicorp.com>