Fix ROOT-5442, wrong normalization of std::vector<myNamespace::myClass1*>::const_iterator

GetPartiallyDesugaredType was 'forgetting' to add full qualification of the
template parameters in some case (where the template paramter in the
QualType was not yet an elaborated type).  Extend the internal interface to
distinguish when we need to add full qualification to the type itself or its
template parameters.
In GetFullyQualifiedType add support for clang::RecordType (possibly pointing to a template instance)