sepolicy: support FST in SoftAP mode

Add rules needed for supporting FST in SoftAP mode:
- Extend the wifi_vendor_hostapd_socket file definition to include
  the hostapd global socket.
- Allow hostapd to send messages back to fstman event socket
- Allow fstman to communicate with hostapd global socket.

Change-Id: Ifbf38e24ff9e0834ef3f3dd8cf70d4e5ce1af4d1