[php-src] Issue #8087: Should \is_file support phar://some.phar?

Issue: https://github.com/php/php-src/issues/8087 Author: brambaud ### Description Hello! I'm not sure if it is a bug or the expected behavior 🤔 The following code: ```php <?php $path = 'phar://'.__DIR__.'/some.phar'; \var_dump( \file_exists($path), \is_file($path), ); ``` Resulted in this output: ``` bool(true) bool(false) ``` But I expected this output instead: ``` bool(true) bool(true) ``` I know that realpath does not work with virtual path like Phar and I wonder if it is the same for is_file? 🤔 If yes then don't hesitate to close the issue and I will open a PR to document it if that's ok with you 😃 ### PHP Version 8.1.0 ### Operating System macOS 12.2