Add ability to control whether KDE Connect listens to Pair Requests from untrusted devices
Summary
Adds an option to start or stop listening to pair requests from untrusted devices. By default, it listens to all requests.
Config option "listening", true by default.
Test Plan
When listening:
All pair requests (including those from untrusted devices) should display a notification
When not listening:
Pair requests from untrusted devices will be rejected without displaying a notification.