Export `Monoid(..)`/`Foldable(..)`/`Traversable(..)` from Prelude

This finally exposes also the methods of these 3 classes in the Prelude
in order to allow to define basic class instances w/o needing imports.

This almost completes the primary goal of #9586

NOTE: `fold`, `foldl'`, `foldr'`, and `toList` are not exposed yet,
      as they require upstream fixes for at least `containers` and
      `bytestring`, and are not required for defining basic instances.

Reviewed By: ekmett, austin

Differential Revision: https://phabricator.haskell.org/D236