Revert "Allow to use non-empty constructor for input types"

[mcg-web]

Reverts #656

[Vincz]

@mcg-web So the idea is that the Arguments Transformer will try to populate Input classes with incoming data. Usually, this Input classes just serve as data objects to handle validation. So, the Arguments Transformer used to instantiate with new InputClass() and It breaks if there is required parameters in the constructor. Instantiating the input class without the constructor prevents this.
But I agree, it's not ideal either to just not call the constructor and can lead to errors. Let's revert it.
There is two options : Maybe when type guessing, we could raise an exception indicating that the Input class cannot be automatically instantiated cause it has required constructor arguments.
Or Maybe we could add a way to add constructor arguments with @GQL\Arg, something like:

class SuperInput {
    constructor(int $superLevel) {
        ....
    }

and use it like that: 

@GQL\Arg(type="SuperInput", constructor={2})