privapps-permission: Grant REQUEST_NETWORK_SCORES to car system apps

NETWORK_REQUEST_SCORES is being changed to a privileged permission from
signature only permission. The wifi stack needs to obtain this permission,
so it can no longer be signature only.

Bug: 113174748
Bug: 135480528
Test: Compiles
Change-Id: Ia824676ee4ddc935346ae22b0aabd6ed4661743f