wifi: Allow configuration of hidden network via QR code reader.

Hidden network ssid is included during bss scan for discovery and
connection. QR code generator currently doesn't set hiddenSSID
value in QR string. Thus, a hidden network at scanner side is
treated as non-hidden, leading to no connection/discovery attempt.

This CL sets QR string appropriately on QR generator.

At QR scanner, on receiving QR data, wifi network is added and an
attempt to connection is made based on current scan results. If this
new configured network is not found in scan results, QR code UI show
error message "Check connection and try again".

Since hidden network is scanned only after addNetwork, lets trigger
connect for hidden network without checking scan entries.

CRs-Fixed: 2492626
Change-Id: Ic10d036085e64ad0340002af8f3b9096f693e393