feat(netxlite): implements NS queries (#734)

This diff has been extracted from https://github.com/bassosimone/websteps-illustrated/commit/eb0bf38957e79fbad198fcdc9f9c7b36f61a8e2c.

See https://github.com/ooni/probe/issues/2096.

While there, skip the broken tests caused by issue
https://github.com/ooni/probe/issues/2098.

internal/cmd/oohelper/internal/fake_test.go

@@ -56,6 +56,10 @@ func (c FakeResolver) LookupHTTPS(ctx context.Context, domain string) (*model.HT
 	return nil, errors.New("not implemented")
 }
 
+func (c FakeResolver) LookupNS(ctx context.Context, domain string) ([]*net.NS, error) {
+	return nil, errors.New("not implemented")
+}
+
 var _ model.Resolver = FakeResolver{}
 
 type FakeTransport struct {