refactor: merge tlsx into netxlite (#403)

Part of https://github.com/ooni/probe/issues/1505

internal/engine/experiment/signal/signal.go

@@ -10,7 +10,7 @@ import (
 
 	"github.com/ooni/probe-cli/v3/internal/engine/experiment/urlgetter"
 	"github.com/ooni/probe-cli/v3/internal/engine/model"
-	"github.com/ooni/probe-cli/v3/internal/engine/netx/tlsx"
+	"github.com/ooni/probe-cli/v3/internal/netxlite"
 )
 
 const (
@@ -111,7 +111,7 @@ func (m Measurer) Run(ctx context.Context, sess model.ExperimentSession,
 	defer cancel()
 	urlgetter.RegisterExtensions(measurement)
 
-	certPool := tlsx.NewDefaultCertPool()
+	certPool := netxlite.NewDefaultCertPool()
 	signalCABytes := []byte(signalCA)
 	if m.Config.SignalCA != "" {
 		signalCABytes = []byte(m.Config.SignalCA)