[App Management] Make notification sublabel displays properly

This CL sets up internationalization and plural string of the notification sublabel.

Bug: 906508
Change-Id: I7190bc7e47e16658bdc035d7488cb2ff151e5ddf
Reviewed-on: https://chromium-review.googlesource.com/c/1390785
Commit-Queue: Cecilia Ni <ceciliani@google.com>
Reviewed-by: Eric Willigers <ericwilligers@chromium.org>
Reviewed-by: calamity <calamity@chromium.org>
Cr-Commit-Position: refs/heads/master@{#620643}
6 files changed