When a InvoiceError is received for a sent BOLT12Invoice, the
corresponding PaymentHash is to be logged. Introduce hmac construction
and verification function for PaymentHash for this purpose.

- The trait defines the public method one may define for creating and
  verifying the HMAC.
- Using a pub trait to define these method allows the flexibility for
  other `OffersMessageHandler` construct to construct the HMAC and
authenticate the message.

Introduce HMAC and nonce calculation when sending Invoice with
reply path, so that if we receive InvoiceError back for the
corresponding Invoice we can verify the payment hash before logging it.

1. Introduced reply_path in BOLT12Invoices to address a gap in error handling.
   Previously, if a BOLT12Invoice sent in the offers flow generated an Invoice Error,
   the payer had no way to send this error back to the payee.
2. By adding a reply_path to the Invoice Message, the payer can now communicate
   any errors back to the payee, ensuring better error handling and communication
   within the offers flow.

1. Updated the Offers Test to check the reply paths in BOLT12 Invoices.
2. Changed the `extract_invoice` return type from `Option<BlindedMessagePath>`
   to `BlindedMessagePath` since all BOLT12Invoices now have a corresponding
   reply path by default.