[POC][model] encrypt payment details

This PR is a proof of payment details encryption concept. The main goal is to save data encrypted to a storage and decrypt before passing it to an action where it should be handled.

I've decided to use [phpseclib/phpseclib](https://packagist.org/packages/phpseclib/phpseclib). Will see if it is good enough.

The extension will encrypt\decrypt all models that implemenst `\ArrayAccess`.