Makes all ArrowPopups AccessibilityTargets.

This currently includes the menu that pops up when
long pressing an app icon in Launcher or Search, or
long pressing Smartspace. Previously, only the menu
for Launcher apps grabbed accessibility focus after
the open animation completed, and now all three do.

Fixes: 145253300
Change-Id: I147b45d38a04ab9a55eee9b5bd5551b4c7185fcf