Add support for serializing fake closures

Description

Fake closures are closures that reference an existing function and are most likely the result of using the First Class Callable syntax function_name(...). It not being serializable makes it harder to move from array/string callable to it.

This limited support should be easier to implement than for arbitrary closures.

Came up as a user-note: https://php.net/manual/en/functions.first_class_callable_syntax.php#129635

该 issue 没有指定源文件、测试或入口点，因此首先定位 PHP 源代码和测试中现有的 closure 序列化处理。确认范围仅涉及使用 First Class Callable syntax 创建的 fake closures；完成的标准是这些 closures 可以被序列化，而不意味着支持任意 closures。