Calls to settle must handle missing or old balance proofs

[hackaugusto]

Problem Definition

The state machine assumes the partner will always successfully call update transfer, and includes both balance proofs in the settlement call, if the update transaction fails then the settle transaction will also fail. To fix this the settle state change should not include the balance proof, but the balance hash, and the balance proof should be recovered from the WAL.

Additionally the state machine assumes always the latest balance proof is used, if an old balance proof is used the state changes in database needs to be searched to find the correct balance proof data

related to: #2129

Split it into two issues:

• Check if partner submitted balance proof before settling #2410
• Recover old balance proof to settle with partner who uses it #2414

[palango]

This is blocked by the conversion to json state which is part of #862