[php-src] Issue #12097: Stringable object should accepted as type-hinted string when in strict-typing mode

Issue: https://github.com/php/php-src/issues/12097 Author: lkankowski ### Description When function/method parameter is type-hinted as string it should also accept any Stringable object. It would be especially useful, when string parameter is nullable, so we can just pass an object instead doing something like: null === $nullableVar ? null : (string) $nullableVar. https://3v4l.org/OBatI#v8.2.10 Sample code: ```php <?php declare(strict_types=1); final class SomeStringable { public function __toString(): string { echo "__toString executed" . PHP_EOL; return "foo"; } } final class SomeClass { public function __construct(public ?string $value) {} } $nullableVar = new SomeStringable(1); //$nullableVar = null; //$result = new SomeClass(null === $nullableVar ? null : (string) $nullableVar); // works $result = new SomeClass($nullableVar); // Fatal error var_dump($result->value); ``` Resulted in this output: ``` Fatal error: Uncaught TypeError: SomeClass::__construct(): Argument #1 ($value) must be of type ?string, SomeStringable given, called in /in/248kv on line 21 and defined in /in/248kv:14 Stack trace: #0 /in/248kv(21): SomeClass->__construct(Object(SomeStringable)) #1 {main} thrown in /in/248kv on line 14 Process exited with code 255. ``` But I expected this output instead: ``` __toString executed string(3) "foo" ``` ### PHP Version 8.2.10 ### Operating System _No response_