Update `createTerminatedStateAccount` of baseInteroperabilityStore

[ishantiw]

Description

The createTerminatedStateAccount function creates an entry in the terminated state substore.

def createTerminatedStateAccount(chainID: ChainID, stateRoot: bytes = EMPTY_BYTES) -> None:    
    if chainAccount(chainID) exists:
        chainAccount(chainID).status = CHAIN_STATUS_TERMINATED
        remove the entry with storeKey = chainID from the outbox root substore

        # If no stateRoot is given as input, get it from the state
        if len(stateRoot) == 0:
            stateRoot = chainAccount(chainID).lastCertificate.stateRoot

        terminatedState = {
            "stateRoot": stateRoot,
            "mainchainStateRoot": EMPTY_BYTES,
            "initialized": True
        }

        # Emit chain status updated event.
        emitEvent(
            module = MODULE_NAME_INTEROPERABILITY,
            name = EVENT_NAME_CHAIN_ACCOUNT_UPDATED,
            data = chainAccount(chainID),
            topics = [chainID]
        )

    # State root is not available, set it to empty bytes temporarily.
    # This should only happen on a sidechain.
    else:
        # Processing on the mainchain
        if ownChainAccount.chainID == CHAIN_ID_MAINCHAIN:
            # If the account does not exist on the mainchain, the input chainID is invalid.
            raise Exception('Chain to be terminated is not valid.')

        terminatedState = {
            "stateRoot": EMPTY_BYTES,
            "mainchainStateRoot": chainAccount(CHAIN_ID_MAINCHAIN).lastCertificate.stateRoot,
            "initialized": False
        }

    create an entry in the terminated state substore with
        storeKey = chainID
        storeValue = encode(terminatedStateAccountSchema, terminatedState)

    emitEvent(
        module = MODULE_NAME_INTEROPERABILITY,
        name = EVENT_NAME_TERMINATED_STATE_CREATED,
        data = terminatedState,
        topics = [chainID]
    )

Acceptance Criteria

• Should pass its unit test

Additional Information

• Related https://github.com/LiskHQ/lips/pull/148