feat(onefingerpan): disable overscroll handelr on non-watch devices

The single finger panning feature is first designed for wear devices and
has overscroll handler to increase the one finger operability. But some
of the manipulations are not suitable on phone or other larger screen
devices, like the horizontal overscroll to change the magnification
scale. On large screen devices we would like to delegate the touch
events to display content when overscroll happens. Therefore, we add a new
config config_support_a11y_fullscreen_magnification_overscroll_handler
and make it false by default, so the FullScreenMagnificationGestureHandler
will not use the OverscrollHandler. Also, we overlay the
config to true on watches, so watches will still have overscroll handler
and keep the original behavior.

NO_IFTTT=checked

Bug: 330192193
Flag: ACONFIG com.android.server.accessibility.enable_magnification_one_finger_panning_gesture DEVELOPMENT
Test: manually
      atest FullScreenMagnificationGestureHandlerTest
Change-Id: Ib1cd7ff8b5d04f4cef11165836e9748262814011