Add support for undocumented reports API endpoints

[shimonenator]

This is another undocumented feature, and it's currently only accessible with Apple's permission, however references to it can be found in the other repositories, such as in https://github.com/guardian/apple-news-analytics-lambda

[iefserge]

Thanks for the PR, this looks good. Can we add tests for the new endpoints though?

[danmakenoise]

@shimonenator (Sorry, same message as other PRs) I'm doing some maintenance work on this repo. I know your PR's are over a year old but are you still interested in getting them merged in, or have you moved on from this library?