witcherscript, annotations: @addMethod forces `public` access modifier

In the current state, no matter the provided access modifier during a `@addMethod` the function is always added using `public`

Using the following code:
```js
class ParentClass {
protected function main() {}
}

class ChildClass {}
```

If the `main` function is added via an annotation:
```js
@addMethod(ChildClass)
protected function main() {}
```

This results in the following error:
```
Function 'main' cannot have a weaker access modifier than in ancestor class 'ParentClass'.
```