feat(platform): introduce abstractions for cross-platform interface statistics and traffic control

Decouple the rate controller from Linux-specific Netlink calls to support other operating systems. This adds a macOS backend for interface statistics and an "observe-only" mode for platforms where traffic shaping is not yet implemented.

src/pinger_icmp_ts.rs

@@ -11,7 +11,7 @@ use crate::time::Time;
 use icmp_socket2::Icmpv4Message;
 use icmp_socket2::Icmpv4Packet;
 use icmp_socket2::packet::WithTimestampRequest;
-use rustix::thread::ClockId;
+use rustix::time::ClockId;
 use std::net::IpAddr;
 use std::time::Instant;