Provide better API for object creation

[s2b]

Currently, it is necessary to extend the built-in ViewHelperResolver implementation, just to provide external DI for created ViewHelper objects. We should provide a better API, which would allow us in the future to define the ViewHelperResolver as internal or even final, since the usual extension points are covered by interfaces and clear APIs.

Possible solution: Provide ViewHelperFactoryInterface and ViewHelperResolverDelegateFactoryInterface, both with a basic implementation.