P3: Implement ReflectionProperty::isPublicSet() (PHP 8.4)

[devin-ai-integration]

Implement isPublicSet() on ReflectionProperty.

The method should return true only when the set visibility is explicitly declared as public(set) and the main visibility is NOT already public. Delegate to php-parser's isPublicSet() on the underlying Property/Param node.

Part of #162

[devin-ai-integration]

Closing: native PHP 8.4 does not have isPublicSet() on ReflectionProperty, so we won't add it to the library.