Add hdevtools linter for haskell

This adds support for the hdevtools haskell linter
https://github.com/hdevtools/hdevtools

The output for hdevtools is near identical to the ghc output so this
also extracts the ghc handler into the handle file and adds tests

* Add testing for previous major release of ghc

ale_linters/haskell/hdevtools.vim

@@ -1,4 +1,4 @@
-" Author: w0rp <devw0rp@gmail.com>
+" Author: rob-b
 " Description: hdevtools for Haskell files
 
 call ale#linter#Define('haskell', {