Add logs and few fixes

[ChristianGabs]

Due some investigation, I've notice it's hard to trace in case your IPN Secret is not valid

• Provide logs in FOSS in case IPN Secret or is incomming webhook request valid
• Do more research on event type as by default is set only for InvoicePaymentSettled
• Investigate partial payment as the last testing the invoice is marking as paid.

[ChristianGabs]

• InvoiceReceivedPayment: Payment has been seen in the mempool (unconfirmed)
• InvoicePaymentSettled: Payment has been confirmed on the blockchain
• InvoiceSettled: Payment is confirmed on the blockchain.

Move the event type to InvoiceSettled, as that will cover cases where partial payments are made due to fees or manual sent, avoiding any issues and also preventing the invoice from being marked as paid.