* Don't wipe local kbs state when kbs stuff fails for change number; its still valid for the old number
* remove remaining error sheet todos
* fix tests
* put rereg mode params into a struct for sharability
* add step and UI handling for when we become deregistered during post-reg steps
* handle dereg when syncing push tokens
* show generic error on kbs backup failure
* handle dereg when restoring from kbs
* handle dereg during profile setup steps
* finalize pni stuff before deregistering
* add comment
* change debug fail to log
* Navigate to verification vc before showing popup so that we don't cancel the nav controller pop
* send a session sms code even if we get interrupted right after session creation
* improve state handling for initial session sms code
* nit: make var fileprivate
* show error when state changed on screen
* Add splash controller for change number flow
* Add copy of change number phone number entry controller
* add copy of change number confirmation view controller
* hook up change number phone number entry screens
* fix header color
* fix change number error view
* add some spacing before error label
* run auto genstrings
* actually fix string comment
* Hook up RegistrationPhoneNumberViewController
* Fix existing tests
* add some new tests; fix test scaffolding bug
* Show an error before going back to phone number entry if the session is invalidated
* Add ability to compute registration recovery password
* Add RegistrationCoordinator
* remove repeat nav controller that evan added
* Scaffolding for RegistrationCoodinator test
* Add first round of RegistrationCoordinator tests, some stuff I needed to get them working, and some fixes to RegistrationCoordinator itself I discovered thanks to the tests
* switch to owsFailBeta
* Add auth credential candidate flow tests, related fixes and additions to coordinator and friends
* Add tests for session based registration path and associated fixes
* PR comment nits
