Use ACTION_SCROLL to scroll TAPL workspace objects

A slow UI thread can cause the first ACTION_DOWN motion event to be handled as a long click before the pointer can be moved for a swipe. Directly using ACTION_SCROLL instead of the usualy ACTION_DOWN/MOVE/UP flow that is sensitive to lag.

Flag: N/A
Bug: 315379864
Test: TaplWorkspaceTest, TaplTwoPanelWorkspaceTest
Change-Id: Ib7fa8c88c953a55b8923ce6a104b5c205c129173