Update handle_message to Accept offers_data as an Input Field

Update handle_message to Accept offers_data as an Input Field

1. Handling Offers Data:
   - Updated `handle_message` to accept `offers_data` as an input field.
   - If `offers_data` is present, it will be utilized by the handler to
     abandon outbound payments that have failed for any reason.

2. Consistency in Custom Message Handling:
   - Updated `handle_custom_message` to accept optional `custom_data`
     for consistency.
   - Note: `custom_data` will remain unused in this PR.