Add Collector class

[samsonasik]

Add Collector to convert:

$newArray = [];

foreach ($data as $datum) {
    if (is_string($datum)) {
        $newArray[] = trim($datum);
    }
}

to:

$transform = fn($datum): string => trim($datum);
$filter = fn($datum): bool => is_string($datum);

$newArray = Collector::process($data,  $transform)
    ->when($filter)
    ->results();