Compatibility feature USE_STRETCH_EDGE_EFFECT_BY_DEFAULT

Bug: 171228096

Added two ChangeIds for stretch overscroll:

USE_STRETCH_EDGE_EFFECT_BY_DEFAULT makes stretch overscroll
the default.

USE_STRETCH_EDGE_EFFECT_FOR_SUPPORTED makes stretch overscroll
the default for applications that use the new EdgeEffect
constructor that accepts an AttributeSet. This indicates
knowledge of stretch overscroll APIs and can be a proxy for
supporting stretch overscroll.

Test: Both flags on apps that support and don't support new api

Change-Id: If2ec832c9656116fe1aa64d33682c489abbde30f