[php-src] Issue #22290: `assert()` failure errors do not correctly handle ASTs with strings containing NUL

Issue: https://github.com/php/php-src/issues/22290
Author: TimWolla

### Description

The following code:

```php
<?php

try {
	$string = "Foo\x00bar";
	assert(!str_contains($string, "\x00"));
} catch (Error $e) {
	echo $e->getMessage(), PHP_EOL;
}
```

Resulted in this output:
```
assert(!str_contains($string, '
```

But I expected this output instead: The closing `'));` should not be cut off. Ideally the NUL byte would be output in escaped form.

### PHP Version

```plain
PHP 8.6.0-dev (cli) (built: Jun 13 2026 14:01:23) (NTS DEBUG)
Copyright © The PHP Group and Contributors
Zend Engine v4.6.0-dev, Copyright © Zend by Perforce
    with Zend OPcache v8.6.0-dev, Copyright ©, by Zend by Perforce
```

### Operating System

_No response_