Add Autoclick cursor area size settings dialog

Replace Autoclick sliderbar with an alert dialog
and radio group to match the new UI requirement.

Screenshot:
 - Click area column:
   go/screenshot-5AfdF7FGghsdiXk
 - Alert dialog:
   go/screenshot-4dgtojcc6lvjtyy

Bug: 390460480
Test: ToggleAutoclickCustomSeekbarControllerTest
Flag: com.android.server.accessibility.enable_autoclick_indicator
Change-Id: Ic79f8833e69dde8d8eb3e945e5acd551d2ee9ff5