[php-src] Issue #12754: Anonymous class without new

Issue: https://github.com/php/php-src/issues/12754 Author: mvorisek ### Description Currently, anonymous classes must be immediatelly instanced. I would be happy if they can declared only and the class name returned (to be assigned or passed directly). # Current syntax ``` class Control {} $controlClass = get_class(new class() extends Control { private static bool $firstCreate = true; public function __construct($defaults = []) { if (self::$firstCreate) { self::$firstCreate = false; return; } throw new Exception('x'); } }); ``` # Expected syntax ``` class Control {} $controlClass = class() extends Control { public function __construct($defaults = []) { throw new Exception('x'); } }; ``` Anonymous classes are used a lot for example in tests and the shorter syntax can make the code simpler. As class is a reserved word, it should be feasible and not ambiguous even with some possible future language features, as the only possible tokens sequence would be class {, class extends or class(.