`require_once` file existence check doesn't account for `chdir`.

Bug report

require_once doesn't account for chdir. Something like this will cause an error even if ../config.php exists:

chdir('..');
require_once('config.php');

Path in require_once() "constants.php" is not a file or it does not exist.

Note that the code snipped will fail because the file probably doesn't actually exist in the sandbox either.

Code snippet that reproduces the problem

https://phpstan.org/r/24b920ed-6231-4278-b401-c3747ccce06f

Expected output

It shouldn't report the file as non-existent.

I wonder if https://github.com/phpstan/phpstan-src/blob/2.3.x/src/File/IncludedFilePathResolver.php can parse any chdir in the current file and add those directories to the list of allowed directories here. Obviously, it's not feasible to check for chdir in any file, but the current file seems reasonable to do.

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Yes. It gives me a lot more confidence that code is okay when reviewing it. Thanks!