MaxEB routines

process_pending_balance_exits

```python
def process_pending_balance_exits(state: BeaconState) -> None:
    state.withdrawal_balance_to_consume += get_validator_churn_limit(state)
    for pending_balance_withdrawal in state.pending_balance_withdrawals:
        if pending_balance_withdrawal.withdrawable_epoch != FAR_FUTURE_EPOCH:
            continue
        
        validator = state.validators[pending_balance_withdrawal.index]
        exiting_balance = Gwei(0)

        if pending_balance_withdrawal.is_exit:
            exiting_balance = state.balances[validator.index]
        else:
            partially_withdrawable_balance = state.balances[validator.index] - MIN_ACTIVATION_BALANCE
            exiting_balance = min(partially_withdrawable_balance, pending_balance_withdrawal.amount)

        if state.withdrawal_balance_to_consume < exiting_balance:
            break

        exit_epoch = compute_activation_exit_epoch(get_current_epoch(state))
        pending_balance_withdrawal.withdrawable_epoch = Epoch(exit_epoch + config.MIN_VALIDATOR_WITHDRAWABILITY_DELAY)
        
        if pending_balance_withdrawal.is_exit:
            validator.exit_epoch = exit_epoch
            validator.withdrawable_epoch = pending_balance_withdrawal.withdrawable_epoch
        
        state.withdrawal_balance_to_consume -= exiting_balance
```