Add InvoiceRequest::verify_using_recipient_data

Add InvoiceRequest::verify_using_recipient_data

Invoice requests are authenticated by checking the metadata in the
corresponding offer. For offers using blinded paths, this will simply be
a 128-bit nonce. Allows checking this nonce explicitly instead of the
metadata. This will be used by an upcoming change that includes the
nonce in the offer's blinded paths instead of the metadata, which
mitigate de-anonymization attacks.