Removed obsolete CCSave payment method

[fballiano]

This PR targets next

CCSave is an old payment method that saved the credit card data directly in the database, this is not used (and nobody should use it) anymore since years.

I've checked my customers' projects and I didn't see any module extending these classes. Although it's possible that there's something out there, it should be part of some functionality that's not in use anymore.

Note: this PR will break the possibility of viewing old orders payed with the ccsave method, as shown in #3441, my opinion is that having merchants still using ccsave in any way could be considered dangerous but probably they don't know (but I think they should and would prefer to know) so at least if the functionaly breaks on their website they will be able to understand that they were having a problematic situation, fix it and most importantly sanitize their database (you don't want to receive a security audit for them to discover you have credit cards stored in your database).

[fballiano]

PHPStan error will be solved by merging #3976

[luigifab]

Perhaps it can be interesting to add a dummy payment method, and a SQL to clean and update db?

[SuSiSonnenschein111]

Magento removed some lines to prevent this hack ... https://blog.sucuri.net/2019/07/magento-killer.html

Woulldn't it be easier to set

protected $_canSaveCc = false;

in Mage_Payment_Model_Method_Ccsave to prevent that CC-info is stored (and re-add tha XML-code, to not break anything)?

This would leave some unused files, but should work like normal CC payment.