BLIK payments improvements

[jakubtobiasz]

Small wins 🏆

• Blik0* classes are renamed to BlikLevelZero* according to this comment
• It is possible to retry a payment with a blik¹
• BLIK token is validated (exactly 6 characters long)

NOTE! Redirecting

1. It is possible to retry a payment with a card

Story:

As a customer who processed through the checkout
But failed to pay with BLIK token as it's expired
When I try to make a payment again using the `Pay` button in the customer panel
I want to be able to choose a BLIK payment and be able to provide my new BLIK token

Reproducer:

1. Complete the checkout, but fail the payment or leave the payment page
2. Go to /en_US/account/orders/
3. Click the Pay button next to your latest order
4. You cannot choose any payment method, as you're getting There's no supported payment method or something like that

[jakubtobiasz]

The middle point has been extracted to a separate issue, where we will cover all payment methods.

#65