network: fix handling of AP flags and enhance for 802.1x

network: fix handling of AP flags and enhance for 802.1x

All WPA APs were getting set as WPA2 due to the check for privacy;
WPA/WPA2 APs *must* set the Privacy bit according to the standard,
so we'd never end up in the case for NMAccessPointSecurity.WPA.

Fix that, and also add flags for WPA[2] Enterprise which we'll
use a bit later for the first-time connect case for 802.1x enabled
access points.