server: implement refunds

[cruzdanilo]

No description provided.

[nfmelendez]

Cryptomate Refund docs:

https://app.theneo.io/cryptomate/api/webhooks/events/card-transaction-refund

Example of a refund in the exa app:

https://exactly-opensearch-do-user-17395075-0.f.db.ondigitalocean.com/app/discover#/doc/e5ba0f50-75f8-11ef-8f79-0b8de70b1495/logs?id=QCxh6JIBbW1ce_94Yy_8

[nfmelendez]

Also needs to support reversals:

https://app.theneo.io/cryptomate/api/webhooks/events/card-transaction-reversal

Example of a reversal in the exa app:

https://exactly-opensearch-do-user-17395075-0.f.db.ondigitalocean.com/app/discover#/doc/e5ba0f50-75f8-11ef-8f79-0b8de70b1495/logs?id=iCyJ-5IBbW1ce_94SzCm

[nfmelendez]

When bin-sponsor send us either REFUND o REVERSAL, the backend has to call the refunder contract with the USDC to refund to the user.

Segment should send an event in each case. Will be 2 events one when we get the event from the bin-sponsor and when actually the refund completes.

Also a refund / reversal should be in the activity screen