Http response headers

## 🚀 Feature Requests

Currently the CacheManager only returns the body of the http response. It will be really useful to be able to retrieve also the respnse headers.

### Contextualize the feature

Some api for example insert the total number of pages (for pagination) in the response header, and currently is impossible to read it.

### Describe the feature
The response file could be a json that contains both the headers and the body of the http response.

### Platforms affected (mark all that apply)
- [x] :iphone: iOS
- [x] :robot: Android

Start by tracing the CacheManager response handling and the response file representation mentioned in the issue. Determine how headers and body can be exposed together without breaking existing body-only callers. Done means callers on iOS and Android can retrieve response headers, including pagination metadata, alongside the cached body.

Scritto dal modello di indicizzazione a partire dal testo della issue.