Add order notes on SessionCanceled

[worais]

All Submissions:

• Does your code follow the Extendables standards?
• Have you written new tests for your changes, as applicable?
• Have you successfully run tests with your changes locally?

Changes proposed in this Pull Request:

This PR adds order notes in the WooCommerce admin whenever a payment made through Amazon Pay is canceled by the buyer or declined by the payment provider.
These notes include detailed information from Amazon’s API such as the reason code and reason description, allowing merchants to clearly understand why a payment failed or was canceled.

Closes #1234

How to test the changes in this Pull Request:

1. Place an order using Amazon Pay and cancel it during the Amazon checkout process.
   → Verify that the order receives a note like:
   "Amazon Pay checkout was canceled. Reason(s): BuyerCanceled"
2. Attempt to complete a payment with an invalid or declined payment method.
   → Verify that the order receives a note like:
   "Amazon Pay charge XYZ Declined. Reason(s): TransactionTimedOut; ProcessingFailure"
3. Check the order status transitions (e.g., failed, pending, canceled) to ensure they remain consistent with existing plugin behavior.

Other information:

• Have you checked to ensure there aren't other open Pull Requests for the same update/change?

Changelog entry

Add order notes to WooCommerce admin when Amazon Pay transactions are canceled by the buyer or declined, including detailed reason codes from Amazon’s API.

[alexiglesias31]

LGTM!