Restrict HAL network access to HALS that manage network hardware

Only HALs that manage networks need network capabilities and network
sockets.

Test: aosp_marlin and aosp_bullhead policy builds. Note: neverallow
      rules are compile time assertions and do not change the
      on-device policy.
Bug: 36185625

Change-Id: Id64846eac24cf72ed91ce775cecb2c75f11b78df

public/hal_neverallows.te

+# only HALs responsible for network hardware should have privileged
+# network capabilities
+neverallow {
+  halserverdomain
+  -hal_bluetooth_server
+  -hal_wifi_server
+  -hal_wifi_supplicant_server
+  -rild
+} self:capability { net_admin net_raw };
+
+# Unless a HAL's job is to manage network hardware, it should not be
+# using network sockets.
+neverallow {
+  halserverdomain
+  -hal_gnss # TODO b/36085168 b/35757613
+  -hal_wifi_server
+  -hal_wifi_supplicant_server
+  -rild
+} domain:{ tcp_socket udp_socket rawip_socket } *;