Add set system proxy support for macOS

common/settings/proxy_windows.go

@@ -1,14 +1,17 @@
 package settings
 
 import (
+	"github.com/sagernet/sing-box/adapter"
 	F "github.com/sagernet/sing/common/format"
 	"github.com/sagernet/sing/common/wininet"
 )
 
-func ClearSystemProxy() error {
-	return wininet.ClearSystemProxy()
-}
-
-func SetSystemProxy(port uint16, mixed bool) error {
-	return wininet.SetSystemProxy(F.ToString("http://127.0.0.1:", port), "local")
+func SetSystemProxy(router adapter.Router, port uint16, isMixed bool) (func() error, error) {
+	err := wininet.SetSystemProxy(F.ToString("http://127.0.0.1:", port), "local")
+	if err != nil {
+		return nil, err
+	}
+	return func() error {
+		return wininet.ClearSystemProxy()
+	}, nil
 }