Renamer now preserves location for IEThingWith list items

Prior to this, in the RenamedSource for

    module Renaming.RenameInExportedType
      (
      MyType (NT)
      ) where

    data MyType = MT Int | NT

The (NT) was given the location of MyType earlier on the line in the
export list.

Also the location was discarded for any field labels, and replaced with
a `noLoc`.

Test Plan: ./validate

Reviewers: bgamari, austin

Reviewed By: bgamari

Subscribers: rwbarton, thomie

GHC Trac Issues: #14189

Differential Revision: https://phabricator.haskell.org/D3968