Implement mainchain Message Recovery Command verfication

[mitsuaki-u]

Description

Add message recovery command verification to mainchain interoperability module.

if terminatedOutboxAccount(trs.params.chainID) does not exist:
    return False

# Check that the CCMs are still pending
for index in trs.params.idxs:
    if index < terminatedOutboxAccount(trs.params.chainID).partnerChainInboxSize:
        return False

# Check the validity of the CCMs to be recovered
for ccm in deserializedCCMs:
    if ccm.status != CCM_STATUS_OK:
        return False

# Check the inclusion proof against the sidechain outbox root
proof = { size: terminatedOutboxAccount(trs.params.chainID).outboxSize,
    idxs: trs.params.idxs,
    siblingHashes: trs.params.siblingHashes}


return RMTVerify( 
  [SHA-256(ccmData) for ccmData in trs.params.crossChainMessages],
  proof,
  terminatedOutboxAccount(trs.params.chainID).outboxRoot
  )

Acceptance Criteria

• Add unit tests for message recovery