Wifi: Allow configuration of Ad-Hoc (IBSS) networks

Show Ad-Hoc (IBSS) networks in the list of available Wi-Fi networks and allow
to connect to or create new Ad-Hoc (IBSS) networks.

This requires the IBSS changes in frameworks/base and external/wpa_supplicant_8

Change-Id: Ie44c47753100bbf8e691446e69b8d31659f64e3b