Kill Type pretty-printer

Here we consolidate the pretty-printing logic for types in IfaceType. We
need IfaceType regardless and the printer for Type can be implemented in
terms of that for IfaceType. See #11660.

Note that this is very much a work-in-progress. Namely I still have yet
to ponder how to ease the hs-boot file situation, still need to rip out
more dead code, need to move some of the special cases for, e.g., `*` to
the IfaceType printer, and need to get it to validate. That being said,
it comes close to validating as-is.

Test Plan: Validate

Reviewers: goldfire, austin

Subscribers: goldfire, thomie, simonpj

Differential Revision: https://phabricator.haskell.org/D2528

GHC Trac Issues: #11660