[php-src] Issue #7900: `never` return type for arrow functions with throw expressions

Issue: https://github.com/php/php-src/issues/7900 Author: weirdan ### Description The following code: ```php <?php fn(): never => throw new Exception; ``` Resulted in this output: ``` Fatal error: A never-returning function must not return in /in/qWWuD on line 3 ``` But I expected this output instead: ``` ``` Obviously, it's caused by implicit return, but throw expressions never actually return. ### PHP Version 8.1.x ### Operating System _No response_