[iOS] Move authentication cells to their folder

This CL moves the cells used by the authentication to their own folder.
It will allow the settings to use those cells later.

Bug: 894791
Change-Id: I2f09eaa853fe782d4400e6f3f5a549ad544a1666
Reviewed-on: https://chromium-review.googlesource.com/c/1373763
Reviewed-by: Jérôme Lebel <jlebel@chromium.org>
Reviewed-by: Sergio Collazos <sczs@chromium.org>
Reviewed-by: Mark Cogan <marq@chromium.org>
Commit-Queue: Gauthier Ambard <gambard@chromium.org>
Cr-Commit-Position: refs/heads/master@{#616290}
51 files changed