Introduce AccessibilityPointerMotionFilter

This new input event filter is used to filter relative motion events
from pointer cursor devices.
This allows the filter to consume some amount of the relative motion
events before the curosor location in the screen is determined by
PointerChoreographer.
Accessibility fullscreen magnification will use this filter.

Bug: 379646448
Bug: 361817142
Test: PointerChoreographerTest
Flag: com.android.server.accessibility.enable_magnification_follows_mouse_with_pointer_motion_filter
Change-Id: I8d5d6bc1fc6b43d08c34906a8fbe843a598d5d16