improve `\Closure::bind()`

```php
<?php

class A {
    private string $prop;
}

$a = new A();

\Closure::bind(function () {
    $this; // infer $this as A
    $this->prop; // can access private, protected, ...
}, $a, $a::class);
```

Drawback: Private properties, private methods should be displayed on the tooltip even if they are accessed in the wrong context.