Reset MouseWheelPhaseHandler state when trackpoint scroll is detected

Background:
* TrackPoint does not issue the FlingCancel/FlingStart events, and
  relies on a Timer to fire GestureScrollEnd events.
* Meanhile, TouchPad does issue both events, and MouseWheelPhaseHandler
  detects detects FlingCancel events, it starts the state machine and
  will never start the timer.

How the issue happens:
The bug happens when a user starts scrolling using TrackPoint + middle
mouse, the user's finger may also touch the touchpad, which is
directly below the middle button, which in turn generate FlingCancel
events. As a result, MWPH's state enter TouchPad processing path, and
will never produce ScrollEnd events.

This creates a situation that from Blink point of view, scroll is still going, and it keeps sending scroll events to the element
where scroll started, even if a user release the button and moved to
another element.

How this fix works:
This CL fix it by finding out if the pointer device can generate Fling
events, and resets the state if it's not (TrackPoint).

Bug: 373441235
Test: covered by unittest.

Change-Id: Ibcb73c66b2463f16b37887e3fdee936216b8df57
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6772346
Reviewed-by: Zoraiz Naeem <zoraiznaeem@chromium.org>
Reviewed-by: Jonathan Ross <jonross@chromium.org>
Commit-Queue: Mitsuru Oshima <oshima@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1494338}