Request API - When a Merchant (Payee) cancels a recurring payment, the API should _not_ return calldata for reducing their Approval

[MantisClone]

Problem

Request API assumes that only the Payer (Subscriber, Employer, Client) cancels a recurring payment, but it's entirely possible that the Payee (Merchant, Employee, Vendor) would cancel.

Solution

Make it possible to specify whether the Payee or Payer is cancelling.

1. If Payer, return calldata to reduce their Approval amount
2. If Payee, don't return approval calldata.