Support updating an existing payment method

Some feedback:

$profile = $payment_method->getBillingProfile();
// skip handling payment methods for anonymous users for now.
if (!$profile || $profile->getOwner()->isAnonymous()) {
  throw new PaymentGatewayException('Updating payment method for anonymous users has not been implemented.');
}

Why are you fetching the profile to check ownership? The payment method has a direct owner since it implements `EntityOwnerInterface`, we should be checking for that.

  'expirationMonth' => $payment_method->card_exp_month,
  'expirationYear' => $payment_method->card_exp_year,

Have you tested this? Without the `->value` at the end you'll be getting a `FieldItemListInterface` object.

Why are you fetching the profile to check ownership?

This is documented as in the comment

// skip handling payment methods for anonymous users for now.

The attached patch corrected the access of the fields.

Yes, the point I was making is that you should not fetch the profile to get the user, the payment method itself has an owner:

if ($payment_method->getOwner()->isAnonymous()) {
  ...
}

Also check if the $user actually exists. That prevents errors when there are dead references.

This version simplified the owner checking.

- Removed the check for anonymous user; after review, since we have the vaulted shopper ID even if it's an anonymous user then we should be safe to update it here. It would be the responsibility of Drupal Commerce whether to expose editing payment methods for anonymous users or not. If that is done, then it can be updated in BlueSnap.
- Made some coding standards improvements.

The commit contains the following compared to the last patch.

- Fixed bug that was sending the data in the wrong format.
- Fixed bug that was deleting shopper names and billing info.

This is now better tested and working as expected. A release will be made after running this and other pending issues on production for some time.

Crediting everybody.

Automatically closed - issue fixed for 2 weeks with no activity.