Building on the demo from COCKPIT-1751, fix up the issues from initial reviewer/user testing enough so that this gets in a landable state, but still without UI review. In particular:

• Less confusing presentation of hidden networks
• Don't duplicate SSIDs with multiple APs
• Intercept failure to connect to a WPA network for which NM does not have a password (desktops use an agent for that). This is annoyingly difficult
• Stabilize the tests. There are a lot of moving parts (hostapd etc.)