[NTP] Handle custom background error states

Handle network, auth, and service errors that can occur when
communicating with the Backdrop and Photos APIs. Display these errors
in the UI. Add the 'message-box' that functions similarly to the
'mv-notice' element.

Redirect the user to sign-in if they are signed-out when selecting
Google Photos.

If the user has no Google Photo albums, link them to the page where
they can create an album.

Bug: 848981, 854418, 854420, 864011
Cq-Include-Trybots: luci.chromium.try:closure_compilation
Change-Id: Ie9d8d246ac9cd0275646c99632f15feb958e423a
Reviewed-on: https://chromium-review.googlesource.com/1136839
Commit-Queue: Kyle Milka <kmilka@chromium.org>
Reviewed-by: Marc Treib <treib@chromium.org>
Cr-Commit-Position: refs/heads/master@{#576164}
11 files changed