Add BaseWifiTracker#disableScanning()

Add a method to disable scanning permanently. This is intended to be a
temporary solution for SysUI to use WifiPickerTracker without invoking
scans all the time in the background.

Bug: 292591403
Test: atest WifiPickerTrackerTest
Change-Id: I34e3f2bb699fc9417a27a01039676c303c2929c0
2 files changed