a11y: Add "Ignore minor cursor movement" autoclick setting

When "Ignore minor cursor movement" is on, the small cursor movement
within the cursor area ring will not interrupt the autoclick timer.

Screenshot: http://b/388845718#comment2

Change-Id: Ib6a8ca8463358a3e2de5ae6be8afd5113a5826ba
Test: ToggleAutoclickIgnoreMinorCursorMovementControllerTest
Bug: b/388845718
Flag: com.android.server.accessibility.enable_autoclick_indicator