lookupInvoice method
      
Future<LookupInvoiceResponse> 
lookupInvoice(
    
- NwcConnection connection, {
- String? paymentHash,
- String? invoice,
Does a lookup_invoice request
Implementation
Future<LookupInvoiceResponse> lookupInvoice(NwcConnection connection,
    {String? paymentHash, String? invoice}) async {
  return _executeRequest<LookupInvoiceResponse>(connection,
      LookupInvoiceRequest(paymentHash: paymentHash, invoice: invoice));
}