Add UiEventLogger to log One-Handed Mode metrics via Westworld.

To log One-Handed Mode events via Westworld by using go/uievent.

Bug: 149366439

Test: manual
Test: Test-drive by command: adb shell cmd stats print-logs
      && adb logcat -s statsd:I | grep ' (90)'
Test: atest SystemUITests:OneHandedEventsTest

Change-Id: If940d0f1901bfdbca6dafec2c0c1391a6fb63461