Support mouse pointer on external displays (1/2)

If input source is mouse, InputTouchMapper and CursorInputMapper will assign
a PointerController which associated with some display.
When dispatch a motion event, it should be assigned the displayId from
PointerController.

- Add getDisplayId for PointerControllerInterface to get the current
  associated display id.
- Add updatePointerDisplay for InputReaderPolicyInterface to find and
  associate the specified display viewport.
- Add test cases for TouchInputMapper and CursorInputMapper.

Bug: 113559891
Test: ActivityView test app
Test: atest inputflinger_tests
Change-Id: I43f848041a7c727f74ad3e00eef546498a7d9314