Migrate to stdlib ECH support

common/badtls/read_wait_ech.go

@@ -1,31 +0,0 @@
-//go:build go1.21 && !without_badtls && with_ech
-
-package badtls
-
-import (
-	"net"
-	_ "unsafe"
-
-	"github.com/sagernet/cloudflare-tls"
-	"github.com/sagernet/sing/common"
-)
-
-func init() {
-	tlsRegistry = append(tlsRegistry, func(conn net.Conn) (loaded bool, tlsReadRecord func() error, tlsHandlePostHandshakeMessage func() error) {
-		tlsConn, loaded := common.Cast[*tls.Conn](conn)
-		if !loaded {
-			return
-		}
-		return true, func() error {
-				return echReadRecord(tlsConn)
-			}, func() error {
-				return echHandlePostHandshakeMessage(tlsConn)
-			}
-	})
-}
-
-//go:linkname echReadRecord github.com/sagernet/cloudflare-tls.(*Conn).readRecord
-func echReadRecord(c *tls.Conn) error
-
-//go:linkname echHandlePostHandshakeMessage github.com/sagernet/cloudflare-tls.(*Conn).handlePostHandshakeMessage
-func echHandlePostHandshakeMessage(c *tls.Conn) error