WIP: replace the backend address related fields/API from udp config, move them to backend udp

config/udp.go

@@ -18,7 +18,6 @@ package config
 
 import (
 	"fmt"
-	"net"
 	"time"
 
 	"gitea.suyono.dev/suyono/netbounce/abstract"
@@ -68,15 +67,3 @@ func (u udpModule) Backend() string {
 func (u udpModule) Timeout() time.Duration {
 	return u.config.Timeout
 }
-
-func (u udpModule) BackendAddr() net.Addr {
-	return udpBackendAddr(u)
-}
-
-func (a udpBackendAddr) Network() string {
-	return "udp"
-}
-
-func (a udpBackendAddr) String() string {
-	return a.config.Backend
-}