[RFC] Add new method to Progress Helper getCurrent()

Please see my example below for my reasoning on how this method can be useful:

```php
$progress = $this->getHelperSet()->get('progress');

$total = 55;
$progress->start($output, $total);
$stepSize = 10;
$lastStepSize = $total % $stepSize; // 5
$i = 0;
while ($i++ <= $total) {
    // ... do some work
    
	if (($i % $stepSize) == 0) {
        // advances the progress bar 10 units or on the final iteration 5 units
        $progress->advance($progress->getCurrent() > $total - $lastStepSize ? $lastStepSize : $stepSize);
	}
}

$progress->finish();
```

I do this work in a listener so it would be nice if the method was part of the helper's api.