Switch Wi-Fi HAL policy to _client/_server

This switches Wi-Fi HAL policy to the design which enables us to
conditionally remove unnecessary rules from domains which are clients
of Wi-Fi HAL.

Domains which are clients of Wi-Fi HAL, such as system_server domain,
are granted rules targeting hal_wifi only when the Wi-Fi HAL runs in
passthrough mode (i.e., inside the client's process). When the HAL
runs in binderized mode (i.e., in another process/domain, with clients
talking to the HAL over HwBinder IPC), rules targeting hal_wifi are
not granted to client domains.

Domains which offer a binderized implementation of Wi-Fi HAL, such as
hal_wifi_default domain, are always granted rules targeting hal_wifi.

Test: Setup Wizard (incl. adding a Google Account) completes fine with
      Wi-Fi connectivity only
Test: Toggle Wi-Fi off, on, off, on
Test: Use System UI to see list of WLANs and connect to one which does
      not require a password, and to one which requries a PSK
Test: ip6.me loads fine in Chrome over Wi-Fi
Bug: 34170079

Change-Id: I7a216a06727c88b7f2c23d529f67307e83bed17f