Use the proper GHC version given by cabal

Proof against NoImplicitPrelude

fix imports

Add ghc-pkg wrapper

Add documentation to new functions

Construct ghc-pkg name from ghc filename

Replace 'ghc' with 'ghc-pkg' in the filename of the ghc executable. This
is better than assuming the executable starts with a 'ghc-' prefix, as
some distros provide a "triple" for the executable, e.g. 'x86_64-redhat-linux-ghc'.

Replacing 'ghc' with 'ghc-pkg' works for these distros as well and,
additionally, we don't have to manually take care of the '.exe' suffix.

Clear package-env for ghc executable path discovery

Refactor 'cabalProcess' function

Undo indentation changes and improve naming

Remove verbose mode from wrapper