Invert the animation over RTL selections

When smart select is performed over right-to-left text (either
standalone or mixed with left-to-right text), the animation should flow
in from the opposite side than what it does over left-to-right text.

Test: manual - verify smart select still works
Test: manual - manually set the layout flags to RTL and verify the
animation behaves as expected
Test: bit FrameworksCoreTests:android.widget.SelectionActionModeHelperTest

Change-Id: I2e7766e7dfe74e0861e91fc50b061da74432aee0