Funds & Designations: send fund to payment gateway meta data

[slewisma]

User Story

As a bookkeeper, I need to know what fund was selected for each donation. Ideally, I need this data to be part of the payment processor's data since that is my "source of truth" for revenue.

Details

The Funds & Designations add-on should have an option to check a box to add the fund or designation data to the meta data that is sent to any payment gateway that supports meta data or custom fields.

Additional Context

This came up in a discussion in the Facebook group for Give. I also have the need with my own clients and though I am comfortable enough with code that I could probably do this myself, it seems like a broad need that spands users that are and are not likely to be comfortable with custom code.

It is desireable that the Fund or Designation is saved in such a way at the payment processor that it can easily be used to sort or filter the data in a spreadsheet or accounting system if the data is exported & imported or synchronized.

Acceptance Criteria

If this enhancement is accepted as a real need, an acceptable solution would mean:

When I check the box to send Funds & Designations choices to the payment gateway, the Fund or Designation appears in the payments data at the payment processor as a custom field or meta data field.