a11y: Implement autoclick drag and move

To perform a dragging type click action 3 key phases need to be
simulated:
1. Clicking and holding the left click button down
 - To simulate this action, only the motion events ACTION_DOWN and
   ACTION_BUTTON_PRESS are initiated.
2. Dragging the object around
 - Here the normal ACTION_HOVER_MOVE events need to be captured and
   transformed into ACTION_MOVE events to make the OS think the left
   click button is still being held down.
 - These ACTION_MOVE events needs to us the same `downTime` as the
   original ACTION_DOWN event.
3. Releasing the left click button
 - To simulate this action, only the motion events ACTION_BUTTON_RELEASE
   and ACTION_UP are initiated.
 - Here as well these events needs to use the same `downTime` as the
   original ACTION_DOWN event.

- Since the MotionEvents are recycled and reused, use a copy of the
  underlying MotionEvent for doing test assertions.

Demo: http://b/388847769#comment2

Bug: b/388847769
Test: AutoclickTypePanelTest
Flag: com.android.server.accessibility.enable_autoclick_indicator
Change-Id: I85522fc9707af6cfea2c21cdb31c8431984b02a5