Remove Type pretty-printer in favor of IfaceType
The Type pretty-printer has a fair amount of code in common with the pretty-printer for IfaceType. Moreover, both cases handle a number of special cases. With the introduction of -fprint-explicit-runtime-reps (#11549 (closed), D1961), there is now an inconsistency between these two.
Let's resolve this inconsistency by eliminating the Type pretty-printer in favor of using the IfaceType printer.