PAY - GST - collection and distribution for ESRA/Site Registry

> _This issue was auto-created as part of the Zenhub sub-issues migration. The original entity was opened on 2022-09-07. For more details see [this post](https://changelog.zenhub.com/migration-of-epics-projects-to-sub-issues-313645?zenhub_entity_id=Z2lkOi8vcmFwdG9yL1plbmh1YkVwaWMvMjA3ODI0)._

This epic is to capture the work needed to handle GST in the Pay API, and any impacted integrations and back-end processes.

To begin, this epic will contain a single research spike with other stories to follow from that research.

**Known Facts:**
In General:
For members of the public, all products must be charged using 4 lines:
1. Statutory Fee
2. Statutory Fee GST
3. Service Fee
4. Service Fee GST

**Questions:**

Are we adding 5% to the cost of each thing, or are partners losing 5% revenue? The service fee will have GST added on top. Comms needed. Then each partner can decide if they want to charge GST on their stat fee.
Are all products subject to GST? --> YES
Do all partners (e.g. crown corps) need us to handle their GST? --> YES but province remits GST to the same GST number unless crown corp
Do we need GST to be togglable at the fee schedule level?

Note:
BCA doesn't charge GST
We should charge GST on the service fee
Sites has GST buiilt in and wants it pulled out

Stats question:
1. What is the dollar amount on the GST on the service fee for a particular partner in a given year?