[php-src] Issue #7845: Stop to automatically cast numeric-string to int when using them as array-key

Issue: https://github.com/php/php-src/issues/7845 Author: VincentLanglet ### Description Currently we have ``` $a = ['01' => '01', '10' => '10']; var_dump($a); // (string) 01 => (string) 01 // (int) 10 => (string) 10 var_dump(array_flip($a)); // (string) 01 => (string) 01 // (int) 10 => (int) 10 var_dump(array_flip(array_flip($a))); // (string) 01 => (string) 01 // (int) 10 => (int) 10 var_dump($a === array_flip(array_flip($a))); // false ``` Is there a reason to do this automatic cast from '10' to 10 when it's an array-key or wouldn't it be better to change this behavior for PHP 9 ? To me it causes unexpected result like this one: ``` <?php declare(strict_types=1); function foo(string $string) {} $array = ['01' => 5, '10' => 6]; $key = array_search(5, $array); foo($key); // works $key = array_search(6, $array); foo($key); // crash ```