[php-src] Issue #12859: Update `@` operator to apply for the next operation only

Issue: https://github.com/php/php-src/issues/12859 Author: mvorisek ### Description The following code: ```php <?php $arr = []; $arr[0]; @strlen($arr[1]); ``` Resulted in this output: ``` Warning: Undefined array key 0 in /tmp/preview on line 5 ``` But I expected this output instead: ``` Warning: Undefined array key 0 in /tmp/preview on line 5 Warning: Undefined array key 1 in /tmp/preview on line 7 ``` This is a feature request to narrow the scope of the supressed error reporting for the next operation only, not the whole expression tree. If supression of the error reporting is wanted for the whole expression tree, @ should be used multiple times.