gnu: Move testing packages from haskell to haskell-check.

gnu: Move testing packages from haskell to haskell-check.

* gnu/packages/haskell.scm (ghc-clock-bootstrap, ghc-tasty-ant-xml,
ghc-tasty-smallcheck, ghc-tasty-quickcheck, ghc-tasty-golden, ghc-tasty,
ghc-tasty-hunit, ghc-tasty-kat, ghc-tasty-th, ghc-tasty-rerun,
ghc-quickcheck-instances, ghc-quickcheck-unicode, ghc-quickcheck-io,
ghc-quickcheck, ghc-test-framework, ghc-test-framework-hunit,
ghc-test-framework-quickcheck2, ghc-test-framework-th, ghc-hunit,
hspec-discover, ghc-hspec-core, ghc-hspec-meta, ghc-hspec, ghc-hspec-contrib,
ghc-hspec-expectations): Move variables to ...
* gnu/packages/haskell-check.scm: ... this new file.
* gnu/local.mk (GNU_SYSTEM_MODULES): Add it.
* gnu/packages/haskell.scm,
gnu/packages/idris.scm,
gnu/packages/version-control.scm,
gnu/packages/wm.scm: Include haskell-check module.