fix: intercept self hold payments based on invoice rather than payment hash

[rolznz]

This PR also fixes a bug where we will fail saying the invoice has already been paid (I think would block wrapped invoices working with LND right now)

TODOs

• undo expiry hack and regenerate invoices
• test in sandbox locally (both wrapped and normal HOLD invoices)
• test with LND (Polar)
• test standard HOLD invoices with LDK (Mutinynet) NOTE: wrapped invoices are not supported yet by LDK-Node.
• test keysend self-payments

Follow ups - move to new issue:

• update Alby Hub to support setting the min_final_cltv_expiry_delta via nwc (needs exposing in our ldk node fork)

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✨ Finishing touches

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