transfers: support WEB files with ACH

[adamdecaf]

PayGate Version: v0.8.0

What were you trying to do?
When trying to send an ACH payment v0.7.x supported creating WEB files. Now after the upgrade they are no longer supported. Only PPD is handled.

What did you expect to see?
Sending WEB files extends the capabilities of PayGate for various needs.

[adamdecaf]

Previously we sent WEB files when that SEC code was specified along with PaymentInformation which was passed directly into the ACH file itself.

An initial implementation could be to have an object to dictate the payment method that must be used. ACH vs Wires, etc along with an object for that payment rail with further fields if needed. Thoughts? /cc @wadearnold

POST /transfers

{
   "paymentMethod": {
     "method": "ACH",
     "ach": {
       "secCode": "WEB"
     }
   }
}