Reduce touch exploration sensitivity.

This change alters touch exploration behavior by requiring that the finger move a number of pixels defined by the system's scaled touch slop value  before it sends a hover event.
Fix: 303677860
Test: atest CtsAccessibilityServiceTestCases:TouchExplorerTest FrameworksServicesTests:TouchExplorerTest

Change-Id: Ib8dd4de60d5c71f38f8873b9c5c2af1d0c6e6010
3 files changed