Chrome OS Settings: extract pin-setting keyboard element.

This CL extracts PIN-setting element into separate Polymer object which
could be used outside of Settings UI.

Bug: 852553
Change-Id: I6da7b1dd0aaffde3b0c220bc2dd1650307904950
Reviewed-on: https://chromium-review.googlesource.com/1196763
Commit-Queue: Alexander Alekseev <alemate@chromium.org>
Reviewed-by: Michael Giuffrida <michaelpg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#588211}
7 files changed