[feature]: Add DeleteInvoice gRPC call

[rsafier]

Is your feature request related to a problem? Please describe. There is no equivalent to DeletePayment for Invoices. Without this developers are only left with two flags to assist in some form of cleanup for CANCELLED invoices which might not fit in with existing patterns well that need more granularity on what is purged from the node.

Describe the solution you'd like Expose DeleteInvoices gRPC call which would allow more granular removal of invoice data.

Describe alternatives you've considered

Adjusting existing process flows for gc-canceled-invoices-on-startup or gc-canceled-invoices-on-the-fly . This is not a major problem on fresh project but in existing workflows this can be significantly more work to fit into either of these options.

Additional context