- apache#6703
- Show errors when `$this` is used in static context(static methods, static closures, static arrow functions)
- Add unit tests

Note:
Check only $this in TypeDeclarations because Frameworks may use `$this` in the global scope.
e.g. CakePHP framework can use `$this`(e.g. `$this->Html->link()`) in the global scope of view files.
(see: https://book.cakephp.org/5/en/views.html)

Example:
```php
class Example {
    private int $field = 1;

    public static function staticMethod(): void {
        $this->field; // error
    }

    public function method(): void {
        $staticClosure = static function() {
            var_dump($this); // error
        };
        $staticArrow = static fn() => $this; // error
        echo $this->field;
    }
}
```