[php-src] Issue #23093: First class callable syntax for instance methods

Issue: https://github.com/php/php-src/issues/23093
Author: rela589n

### Description

Consider the following code:

```php
class Booking
{
    public function getFreeCancellationDeadline(): ?\DateTimeImmutable
    {
          //  ....
    }
}
```

Then, you'd like to have a closure:

```php
fn (Booking $b): ?\DateTimeImmutable => $b->getFreeCancellationDeadline();
```

It would be much neater to have it like this:

```php
Booking::getFreeCancellationDeadline(...);
```

This is the exact form in which PhpStorm IDE copies the method reference ("Copy Reference" on the method - Ctrl+Alt+Sft+C).