Expand the animation from the user's last touch point

The Smart Select animation now expands from the spot the user last
lifted their finger.

In order to achieve this, the last up event coordinates need to be
tracked in Editor.

Since it's possible to trigger Smart Select by having the second of the
two taps outside any of the rectangles, the touch point gets moved into
the nearest rectangle and the animation starts from that point.

Test: manual - try out Smart Select by touching different words at
different points
Test: manual - try to trigger Smart Select with a double tap where the
second tap is outside of the word
Test: bit FrameworksCoreTests:android.widget.SelectionActionModeHelperTest
Test: bit CtsViewTestCases:android.view.textclassifier.cts.TextClassificationManagerTest
Test: bit FrameworksCoreTests:android.widget.TextViewActivityTest
Test: bit CtsAccessibilityServiceTestCases:android.accessibilityservice.cts.AccessibilityTextTraversalTest
Change-Id: I96844e8307554b010b476673820f98dae09c0cc3