Consider getting rid of ActionResultsHelper

[yishaigalatzer]

(also IActionResultHelper) It started as an extensibility and convenience point. Looks not that interesting at this point.

Either we add all the helpers on it, or remove it completely

@davidfowl @loudej - thoughts

[yishaigalatzer]

Chatted with @davidfowl - Will show a design (either fleshing more things in the helper, or getting rid of it).

The meta question is what is the purpose of the POCO controller

1. Should it be easy to return views/json etc. Should we
2. Should it be easy to return objects (like the previous try of int => status code, string => text content, Other objects => Json/Conneg, IActionResult ...
3. Should is be easy to build another base controller without deriving from Controller