Move IEx.ANSIDocs > IO.ANSI.Docs
Fix IO.ANSI.Docs and its corresponding test
Fix other references to IO.ANSI.Docs
Define IEx.dont_display_result in IO.ANSI.Docs

This removes all remaining references to IEx from IO.ANSI.Docs and makes the dont_display_result function more generic by replacing the "in iex" bit with "in output".