Fix ImpossibleCheckTypeFunctionCallRule for is_subclass and is_a

[VincentLanglet]

Improved strategy for #3404

The main idea is that always true error can always be reported if the second param is a Constant class-string (or union of them).

I included a non regression test from
#3404 (comment)

Closes phpstan/phpstan#3979
Closes phpstan/phpstan#8464

[gnutix]

I don't know if this PR would fix this, but I just upgraded to the latest PHPStan version and this new error popped up:

Call to method ReflectionClass<object>::isSubclassOf() with 'App\\Application\\Shared\\
Query\\Filter\\ListQuery' will always evaluate to false.

for this code :

#[Override]
    public function supports(Model $model): bool
    {
        $type = $model->getType();
        if ('object' !== $type->getBuiltinType()) {
            return false;
        }

        $class = $type->getClassName();
        if (null === $class || !class_exists($class)) {
            return false;
        }

        $reflection = new ReflectionClass($class);

        return $reflection->isSubclassOf(ListQuery::class) ? ... : ...;

Should I open a separate bug?

[ondrejmirtes]

@gnutix That is unrelated, and most likely a consequence of phpstan/phpstan#12459