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/reflector_selector.rs

@@ -2,11 +2,11 @@ use crate::SHUTDOWN;
 use crate::metrics::{Metric, MetricsSender};
 use crate::util::{ArcMutex, MutexExt, RwLockExt};
 use crate::{Config, ReflectorStats};
+use flume::Receiver;
 use log::{debug, info};
 use std::collections::HashMap;
 use std::net::IpAddr;
 use std::sync::atomic::Ordering;
-use std::sync::mpsc::Receiver;
 use std::sync::{Arc, RwLock};
 use std::thread::sleep;
 use std::time::Duration;