Create a controller for QR Code Scanner in android

This change adds a new controller that can enable/disable the entry
points for invoking a generic QR code scanner. This controller manages
the following:
1. Enabling/disabling the lock screen entry point
2. Enabling/disabling the quick settings entry point
3. Enabling/disabling the settings for lock screen entry point
4. Any changes to the QR code scanner device config

Bug: 200536509
Test: atest QRCodeScannerControllerTest

Change-Id: I6d1001e7597576f39f51f8cf4ef763fcc253423c