Add support for Pay & Tokenize

[loueranta-paytrail]

Paytrail API now supports Pay & Tokenize:

"This method is an alternative way to add (tokenize) a card, which combines a payment and adding a new card to allow getting the card token after a successful payment with a single request."

https://docs.paytrail.com/#/?id=pay-and-add-card

Let's add support for this functionality to the plugin after the PHP-SDK has been updated accordingly:
paytrail/paytrail-php-sdk#80