Implement the pause/block app accessbility requirement for Chrome Vox.

If the app is paused or blocked, announce 'Paused' or 'Blocked' for
Chrome Vox, when the icon item is selected/focused from app list, shelf
or searchbox.

The block status has higher priority. When the app is paused and
blocked, announce 'Blocked'.

This CL modifies the search box result to add 'Paused' or 'Blocked' to
the accessible name.

BUG=1144384

Change-Id: I1388a021a169cf332b86bfd892d7ccde990fc805
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2545908
Commit-Queue: Nancy Wang <nancylingwang@google.com>
Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#828768}