TUID resolution ignores reference name

[HeikoKlare]

Some time ago, we added the reference name to the TUID to make the TUID more unambiguous and improve resolution.
While the TUID calculator adds the reference name to the TUID (at least in cases in which the attribute is set), the resolver does not use the reference name for restricting the lookup. In fact, it ignores it and thus potentially procudes false results.

We have to update the TUID resolver to use the reference name for retrieving the matching element. Besides, this also improves resolution performance. Furthermore, we have to update the TUID calculation to also add the reference name when the attribute is not set.