Move a method that creates constant ranges relative to another constant range

Move a method that creates constant ranges relative to another constant range
per icmp predicate out of predsimplify and into ConstantRange.

Add another utility method that determines whether one range is a subset of
another. Combine with the former to determine whether icmp pred range, range
is known to be true or not.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@75357 91177308-0d34-0410-b5e6-96231b3b80d8