Added dampening logic to caluclate the distance to
overscroll.
Updated StretchEffect to support independent
maximum stretch amounts for the x/y axis
Removed debugging parameters to configure
stretch distance since they are no longer
used. Removed hidden API calls to configure
stretch distance in ScrollView/HorizontalScrollView
Bug: 179047472
Test: re-ran EdgeEffectTests
Change-Id: I4698669273d364695a21c2cce00ec2cfec41b2cc
a225d21f7d