Move tokio_kcp to local files

src/plugins/kcp/utils.rs

@@ -0,0 +1,10 @@
+use std::time::{SystemTime, UNIX_EPOCH};
+
+#[inline]
+pub fn now_millis() -> u32 {
+    let start = SystemTime::now();
+    let since_the_epoch = start
+        .duration_since(UNIX_EPOCH)
+        .expect("time went afterwards");
+    (since_the_epoch.as_secs() * 1000 + since_the_epoch.subsec_millis() as u64 / 1_000_000) as u32
+}