Fix a couple issues related to drag and drop in Touch Exploration mode

=> The framework no longer sends touch events after double-click and hold, and instead only triggers a single long-press event
=> As a result of the above, there is some additional state that must be set for accessible drag and drop, and further, we no longer initiate a drag in response to long press when Touch Exploration is on.

Test: manual

issue b/148308758

Change-Id: I26ab90b807965f31c8de93d451130410169f2fb0