[input-output-hk/cardano-sl] [CDEC-513] Move Pos.Core.Genesis.Canonical to Pos.Util.Json.Canonical (#3445)

erikd commented on this pull request.

> {-# OPTIONS_GHC -fno-warn-orphans #-}

+{-# LANGUAGE RecordWildCards #-}

Is that still needed? If not please kill it :)