cli: error classification refactoring (#386)

* make errorx classifier less dependent on strings

* adapt errorx tests

* added syserror comment

* localized classification of quic errors

* localized classification of resolver errors

* (fix) move "no such host" error to global classifier

* moved x509 errors to local TLS error classifier

* added qtls error classification for quicdialer

* add Classifier to SafeErrWrapperBuilder

* windows/unix specific files for errno constants

* added errno ETIMEDOUT, tests

* added TLS alert constants

* added FailureSSLHandshake test, improved switch style

* added more network based system error constants for future use

* (fix) import style

* (fix) errorx typos/style

* (fix) robustness of SafeErrWrapperBuilder, added comments

* (fix) reversed unnecessary changes, added comments

* (fix) style and updated comment

* errorx: added future re-structuring comment

* (fix) typo TLS alert code 51

* added comment

* alert mapping: added comment

* Update errorx.go

* Update internal/engine/netx/errorx/errorx.go

Co-authored-by: Simone Basso <bassosimone@gmail.com>

internal/engine/netx/quicdialer/saver_test.go

@@ -85,7 +85,7 @@ func TestHandshakeSaverSuccess(t *testing.T) {
 
 func TestHandshakeSaverHostNameError(t *testing.T) {
 	nextprotos := []string{"h3"}
-	servername := "wrong.host.badssl.com"
+	servername := "example.com"
 	tlsConf := &tls.Config{
 		NextProtos: nextprotos,
 		ServerName: servername,