ConnectToNetworkNotification: Disallow connect from lock screen

Avoids malicious usage of the notification to add a saved wifi network
without unlocking the device.

Bug: 172584372
Test: Manual:
ONA notification not shown in the lockscreen. Visible when the device
is unlocked.

Change-Id: I760cd4303b846a214737edc49254f6327e05d357
Merged-In: I760cd4303b846a214737edc49254f6327e05d357
(cherry picked from commit ec2ba25598cec3403460ee6d5f6b74399fbca598)