UNC: improved ongoing check for updated foreground service notifications
When foreground service notification gets updated it may be missing
foreground service flag. This flag is set later in the process by
WorkerHandler which is too late for us (as our hook will most likely get
processed earlier than WorkerHandler runnable). 
This affected mainly apps that dynamically update the contents of
foreground service notifications (such as GPS Status, etc...) resulting
e.g. in ActiveScreen heads up constantly popping up for them as UNC was
not aware of that they were actually ongoing.

Solution: make sure to check whether previous notification that is
getting updated had a foreground service flag set the same way
WorkerHandler does according to Line 1776 at
https://android.googlesource.com/platform/frameworks/base/+/android-4.4.4_r2.0.1/services/java/com/android/server/NotificationManagerService.java