refactor: replace std::sync::mpsc with flume for improved channel performance

Migrate internal message passing to flume to leverage better performance and additional features like eventual fairness and selection.

src/ratecontroller.rs

@@ -4,6 +4,7 @@ use crate::netlink::{Netlink, NetlinkError, Qdisc};
 use crate::time::Time;
 use crate::util::{ArcMutex, ArcRwLock, MutexExt, RwLockExt};
 use crate::{Config, ReflectorStats};
+use flume::Sender;
 use log::{debug, info, warn};
 use rustix::thread::ClockId;
 use std::collections::HashMap;
@@ -11,7 +12,6 @@ use std::fs::File;
 use std::io::Write;
 use std::net::IpAddr;
 use std::sync::atomic::Ordering;
-use std::sync::mpsc::Sender;
 use std::thread::sleep;
 use std::time::{Duration, Instant};
 use thiserror::Error;