Implement sendInternal method in interoperability store

[mitsuaki-u]

Description

Create and send a cross chain message:

sendInternal(feeAddress, moduleID, crossChainCommandID, receivingChainID, fee, status, params):
    # Processing on the mainchain
    if ownChainAccount.ID == MAINCHAIN_ID:
        # Chain has to exist on mainchain
        if chainAccount(receivingChainID) does not exists:
            return False
        partnerChainID = receivingChainID
    # Processing on a sidechain
    else:
        # Check for direct channel
        if chainAccount(receivingChainID) does not exists:
            partnerChainID = mainchainID
        else:
            partnerChainID = receivingChainID

    # Chain must be live; This checks is always on the receivingChainID
    if not isLive(receivingChainID):
        return False
    # Chain status must be active
    if not chainAccount(partnerChainID).status == CHAIN_ACTIVE:
        return False

    # Create cross-chain message
    ccm = {
        "nonce": ownChainAccount.nonce,
        "moduleID": moduleID,
        "crossChainCommandID": crossChainCommandID,
        "sendingChainID": ownChainAccount.ID,
        "receivingChainID": receivingChainID,
        "fee": fee,
        "status": status,
        "params": params
    }

    if validateFormat(ccm) == False:
        return False

    for each module mdl for which beforeSendCCM exists:
        mdl.beforeSendCCM(feeAddress, ccm)
        if the previous call fails:
            return False

    addToOutbox(partnerChainID, ccm)
    ownChainAccount.nonce += 1
    
    return True

Acceptance Criteria

• Add unit tests for sendInternal