Multiple serializers for one model about surrealist

[AlessandroMinali]

I like this option and the PR but I think we can do better than tag.

I think as works for both setting and using.
We could differentiate using by making the option with.
@nesaulov ?

Just a minor nitpick.

[nesaulov]

@AlessandroMinali I don't think with will do, it just looks bad (two withs):

class Something
  include Surrealist
  
  surrealize_with SomethingSerializer, with: :api
end

as seems okay, but honestly I don't consider it to be better than tag, I think tag is more semantically descriptive in our case.

User.find(34).surrealize(as: :api)
User.find(34).surrealize(tag: :api)