Protect usage data with OP_GET_USAGE_STATS.

APIs that return package usage data (such as DropBoxManager) must
ensure that callers hold both the PACKAGE_USAGE_STATS permission
and the OP_GET_USAGE_STATS app-op.

Bug: 78355661
Test: Search output directory for binaries that have READ_LOGS but not
USAGE_STATS and find none.

Change-Id: I85e3bad680bb510439d73c7db5cc50cdcb7bbb42