Relax node type change restrictions to allow reparenting without changing the effective node type

Case in point: HIPPLUG-1407 for which we want to allow the reparenting of selection:listitem > nt:base to selection:listitem > hippo:compound.
As hippo:compound > nt:base without adding any other type definitions, effectively and technically such a change really is and should be trivial, but currently the checks in Jackrabbit NodeTypeDiff doesn't allow it.

The intend is to improve and relax the check in NodeTypeDiff#supertypesDiff() to allow for such "no-impact" changes, by checking and comparing the effective parent types instead of just the list of parent names.