Do not report undefined property in isset/empty/?? for types without class names

[phpstan-bot]

Closes phpstan/phpstan#13539

When checkDynamicProperties is enabled (e.g. via phpstan-strict-rules), PHPStan incorrectly reported "Access to an undefined property" for chained isset() checks on mixed types.

The scenario:

$tmp = json_decode($x, false); // mixed
if (!isset($tmp->foo) || !isset($tmp->bar)) { }

The first isset($tmp->foo) narrows mixed to object&hasProperty(foo). In the falsey branch (where we evaluate the right side of ||), the second isset($tmp->bar) triggers AccessPropertiesCheck which calls pickProperty on an IntersectionType(ObjectWithoutClassType, HasPropertyType(foo)). Since this type has no concrete class names, pickProperty returns null, and the code treated that as "property definitely doesn't exist" — reporting a false positive.

The fix adds a check: when the type has no class names (bare object, object&hasProperty(...)) we skip the dynamic property check in isset/empty/?? context, since we cannot know what properties such a type might have. For concrete classes, the existing behavior is preserved.

This also fixes the related bug #13529 which had a test expecting the buggy behavior.

Construct	Before	After
!isset($tmp->foo) || !isset($tmp->bar)	false positive	no error
isset($tmp->foo, $tmp->bar)	no error	no error
isset($tmp->foo) && isset($tmp->bar)	no error	no error
$tmp->bar ?? null after isset	false positive	no error
empty($tmp->bar) after isset	false positive	no error
Concrete class with #[AllowDynamicProperties]	reports	reports (preserved)