Allow additional wpa_supplicant.conf in client mode

[mame82]

Allow providing a wpa_supplicant.conf file in WiFi client (station) mode, to attempt to connect to multiple known access points.

It has to be tested if this could still be combined with failover mode. Otherwise usage will be restricted to client mode

[mame82]

Not needed, data structures of WiFi settings allow multiple target networks (backed by an array).
The feature isn't visible from the WebClient or CLI, as the array is always filled with a single BSSCFG (target SSID and PSK)

[SymbianSyMoh]

Any updates on this one? I was about to open a feature request to add the capability to the Client Mode to search and connect to more than one defined APs!