PunyencodeAddressTest: add additional test method
PunyencodeAddressTest: add additional test method

This new test method covers a range of cases where the `PHPMailer::punyencodeAddress()` method should (and does) return the original input value unchanged.

This test does not require the `mbstring` extension or `idn_to_ascii()` function to be available, which is why it has been set up as a separate test with a separate data provider.

jimjag/PHPMailer,PHPMailer/PHPMailer,nawawi/PHPMailer,PHPMailer/PHPMailer,nawawi/PHPMailer,jimjag/PHPMailer