Holds if GVN t1 subsumes GVN t2. That is, it is possible to replace all
type parameters in t1 with some GVNs (possibly type parameters themselves)
to make the two substituted terms equal.
Import path
import semmle.code.csharp.Unificationpredicate subsumes(ConstructedGvnType t1, ConstructedGvnType t2)