Expose privacy mode in public API

[antoninbiret]

For now the public API accepts a String for the privacy mode setter however you internally deal with a struct PA.Privacy.Mode. It would probably be better to expose this struct or expose an enum (as the Privacy.VisitorMode in the ATInternet SDK) in order to let the compiler check if the privacy mode is managed. We did the mistake while migrating from ATInternet as the underlying string for the privacy mode does not use the same case.

Looking forward to read your feedback.

Antonin.