Summary:
In order to disambiguate names from different modules, qualify all names
that don't originate in the current module.

Also update docs for QueryQualifyName

Test Plan: validate

Reviewers: simonpj, bgamari

Reviewed By: simonpj

Subscribers: rwbarton, thomie, carter, tdammers

GHC Trac Issues: #15269

Differential Revision: https://phabricator.haskell.org/D4852

(cherry picked from commit d42eef34)