feat: tlsping and tcpping using step-by-step (#815)

## Checklist

- [x] I have read the [contribution guidelines](https://github.com/ooni/probe-cli/blob/master/CONTRIBUTING.md)
- [x] reference issue for this pull request: https://github.com/ooni/probe/issues/2158
- [x] if you changed anything related how experiments work and you need to reflect these changes in the ooni/spec repository, please link to the related ooni/spec pull request: https://github.com/ooni/spec/pull/250

## Description

This diff refactors the codebase to reimplement tlsping and tcpping
to use the step-by-step measurements style.

See docs/design/dd-003-step-by-step.md for more information on the
step-by-step measurement style.

internal/netxlite/utls_test.go

@@ -19,8 +19,7 @@ func TestNewTLSHandshakerUTLS(t *testing.T) {
 	if logger.DebugLogger != log.Log {
 		t.Fatal("invalid logger")
 	}
-	errWrapper := logger.TLSHandshaker.(*tlsHandshakerErrWrapper)
-	configurable := errWrapper.TLSHandshaker.(*tlsHandshakerConfigurable)
+	configurable := logger.TLSHandshaker.(*tlsHandshakerConfigurable)
 	if configurable.NewConn == nil {
 		t.Fatal("expected non-nil NewConn")
 	}