Integrate the client library into the OONI Probe client: Engine

[jbonisteel]

This is an epic for the Anon credentials project

Due date: September 30th

We will do all the work (including release engineering) required to integrate the libraries into OONI Probe. This means integrating the library into the various OONI Probe apps and making any changes to the API that are needed to make the integration possible.

Output: links to specific commits for the integration work in our various probe-related repositories.