ShapeAppearanceModel.
Prior to this change, ShapeAppearanceModel#setAllCorners() and
ShapeAppearanceModel#setAllEdges() set all four corners or edges to the same
CornerTreatment or EdgeTreatment. This change creates deep copies for each
corner/edge treatment to avoid bugs caused by silently reusing the mutable
object.
PiperOrigin-RevId: 222413898