Peppol / E-Invoice - Allow sending Credit Note via Peppol network

What version of Invoice Ninja are you running? ie v4.5 / v5
v5.12.30

What environment are you running?
Self hosted

Have you searched existing issues/requests?
Yes

Screenshots

<img width="553" height="168" alt="Image" src=" />


Additional context
The e-invoice capability allows sending invoices via Peppol. However, credit note do not have the capability to be send via Peppol.

In Peppol, a credit note must be sent as a <ubl:CreditNote>, not as a <ubl:Invoice>.