wifi: package hostapd and wpa_supplicant into apex

* This is now possible on Android 15 QPR2. Use cuttlefish as reference.
  https://android.googlesource.com/device/google/cuttlefish/+/refs/tags/android-15.0.0_r20/apex/com.google.cf.wpa_supplicant/
* Create local copies of the service entries. Generally creating the
  directories for wireless subsystem happens on trigger 'on post-fs-data'.
  Since apexd for non-bootstrap APEXs starts 'on post-fs-data', this
  trigger is not available for vendor APEX packages. Use trigger
  'apex.all.ready=true' instead which is later still within post-fs-data.
  https://source.android.com/docs/core/ota/vendor-apex#init-scripts
* Create a local copy of wpa_supplicant_overlay.conf. It hasn't been updated
  in ten years in hardware/broadcom/wlan. TODO: Check relevance.

wifi/apex_file_contexts_supplicant

@@ -0,0 +1,3 @@
+(/.*)?                    u:object_r:vendor_file:s0
+/etc(/.*)?                u:object_r:vendor_configs_file:s0
+/bin/hw/wpa_supplicant    u:object_r:hal_wifi_supplicant_default_exec:s0