Add CTS permissionpolicy for GET_BACKGROUND_INSTALLED_PACKAGES.

Edit: Removed adding role change, as feature flags is not in a
consistent state. Will add role change later.

New permission enables BICS to provide caller with all silently
installed apps for all users on a device without needing caller to be
granted overly permissive access.

For more info: go/bic-v

Bug: 296060433
Test: m
Change-Id: I4c5c0d5a7b60edcc53d3098d3125a7654846d608