Add ability to check if hostname is valid for a specific cert

This commit adds two new bifs, x509_check_hostname and
x509_check_cert_hostname. These bifs can be used to check if a given
hostname which can, e.g., be sent in a SNI is valid for a specific
certificate.

This PR furthermore modifies the ssl logs again, and adds information
about this to the log-file. Furthermore we now by default remove the
server certificate information from ssl.log - I doubt that this is often
looked at, it is not present in TLS 1.3, we do still have the SNI, and
if you need it you have the information in x509.log.

This also fixes a small potential problem in X509.cc assuming there
might be SAN-entries that contain null-bytes.

Baseline update will follow in another commit.

src/Val.cc

@@ -986,6 +986,12 @@ string StringVal::ToStdString() const
 	return string((char*)bs->Bytes(), bs->Len());
 	}
 
+string_view StringVal::ToStdStringView() const
+	{
+	auto* bs = AsString();
+	return string_view((char*)bs->Bytes(), bs->Len());
+	}
+
 StringVal* StringVal::ToUpper()
 	{
 	string_val->ToUpper();