...by letting their getByHierarchicalName methods return information about
UNO constants as X(Constant)TypeDescription values, just as for (alomst -- see
the odd enum member case) all other entities.  This will make future changes in
this area easier.

The only affected client I could find so far is the core reflection service, but
there might be more that I overlooked.

Change-Id: I6731f2914773d49e33eeaec6e256ff2e5409ad2d