Compatibility with JSONAPI::Authorization (Resource Caching)

This issue is a (choose one):

• Feature request.

Checklist before submitting:

• I've searched for an existing issue.
• The feature I'm asking for is compliant with the JSON:API spec.

Description

JSONAPI::Authorization is a pundit based authorization tool that works out-of-the-box with jsonapi-resources' ActiveRecord backed resources.
The problem is with Cached Resource as it does not have a model key.

JSONAPI::Authorization's related issue https://github.com/venuu/jsonapi-authorization/issues/67

Features:

Exposing the original model into cache in CachedResourceFramgment(https://github.com/cerebris/jsonapi-resources/blob/master/lib/jsonapi/cached_response_fragment.rb#L87) would solve the problem easily – not sure about the cons.

I have a working solution in my fork so I can submit a PR If you are OK with the idea.

Beginne bei lib/jsonapi/cached_response_fragment.rb etwa bei Zeile 87 und prüfe, wie Cached Resource die Ressource derzeit darstellt. Sieh dir das verlinkte JSONAPI::Authorization-Issue und die gemeldete Fork-Lösung an und bestimme dann, ob das Offenlegen des ursprünglichen Modells den fehlenden Modellschlüssel ohne nachteilige Auswirkungen behebt. Als abgeschlossen gilt die Aufgabe, wenn Cached Resource mit dem Ressourcen-Caching von JSONAPI::Authorization funktioniert.