[native] Move final registration step to RegistrationTerms

Summary:
This diff makes it so RegistrationTerms is the last screen in the wizard, and so that pressing the "Register" button triggers registration.

Depends on D8162

Test Plan: I tried going through the wizard and confirmed it works

Reviewers: atul, ginsu

Reviewed By: atul

Subscribers: tomek

Differential Revision: https://phab.comm.dev/D8163