fix(netxlite/dns): more stricly mirror stdlib error strings (#513)

This diff attempts to modify the errors reported by our custom
resolver by matching more strings from the stdlib.

Part of https://github.com/ooni/probe/issues/1733 and diff has been
extracted from https://github.com/ooni/probe-cli/pull/506.

internal/netxlite/errorsx/errno.go

@@ -1,5 +1,5 @@
 // Code generated by go generate; DO NOT EDIT.
-// Generated: 2021-09-27 14:20:26.411929 +0200 CEST m=+0.233208042
+// Generated: 2021-09-27 15:57:58.500515 +0200 CEST m=+0.304199251
 
 package errorsx
 
@@ -50,6 +50,9 @@ const (
 	//
 	FailureDNSBogonError           = "dns_bogon_error"
 	FailureDNSNXDOMAINError        = "dns_nxdomain_error"
+	FailureDNSRefusedError         = "dns_refused_error"
+	FailureDNSServerMisbehaving    = "dns_server_misbehaving"
+	FailureDNSNoAnswer             = "dns_no_answer"
 	FailureEOFError                = "eof_error"
 	FailureGenericTimeoutError     = "generic_timeout_error"
 	FailureQUICIncompatibleVersion = "quic_incompatible_version"
@@ -94,6 +97,9 @@ var failuresMap = map[string]string{
 	"wrong_protocol_type":            "wrong_protocol_type",
 	"dns_bogon_error":                "dns_bogon_error",
 	"dns_nxdomain_error":             "dns_nxdomain_error",
+	"dns_refused_error":              "dns_refused_error",
+	"dns_server_misbehaving":         "dns_server_misbehaving",
+	"dns_no_answer":                  "dns_no_answer",
 	"eof_error":                      "eof_error",
 	"generic_timeout_error":          "generic_timeout_error",
 	"quic_incompatible_version":      "quic_incompatible_version",