GitLab

This adds the contact visibility component which will be hosted in the
on-boarding experience as well as in settings. This is just a roughed
in version of the component without the back end/mojo functionality to
retrieve contacts yet. String, a11y, and final specs are still pending.
Eventually this component we need to support a compact layout for
on-boarding and a full layout for settings.

Screenshots:
Zero-state (no-selection):
https://screenshot.googleplex.com/079678b4-8a72-43db-a46b-b853286a41ba.png
All contacts selected:
https://screenshot.googleplex.com/cfd1c5ee-565a-4908-99f1-cd3b7ef5683a.png


Change-Id: I6c3558e8f747fade5ee7f7d0c0e0d5a710d77457
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2352520Reviewed-by: Kyle Horimoto <khorimoto@chromium.org>
Reviewed-by: Regan Hsu <hsuregan@chromium.org>
Commit-Queue: James Vecore <vecore@google.com>
Cr-Commit-Position: refs/heads/master@{#799162}