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

首先跟踪 CacheManager 的响应处理流程，以及 issue 中提到的响应文件表示方式。确定如何在不破坏现有仅使用 body 的调用方的情况下，同时公开 headers 和 body。完成标准是 iOS 和 Android 上的调用方都能在获取缓存 body 的同时获取响应 headers，包括分页元数据。

由索引模型根据 Issue 内容生成。