[ConstantRange] Rename isWrappedSet() to isUpperWrapped()

Split out from D59749. The current implementation of isWrappedSet()
doesn't do what it says on the tin, and treats ranges like
[X, Max] as wrapping, because they are represented as [X, 0) when
using half-inclusive ranges. This also makes it inconsistent with
the semantics of isSignWrappedSet().

This patch renames isWrappedSet() to isUpperWrapped(), in preparation
for the introduction of a new isWrappedSet() method with corrected
behavior.

llvm-svn: 357107