enable to customize between cabal repl and cabal new-repl

[ukari]

Added a custom variable haskell-process-cabal-repl-command to support switch between cabal repl and cabal new-repl.

usage (switch to cabal new-repl):

(setq haskell-process-cabal-repl-command 'new-repl)
;; set `haskell-process-args-cabal-repl` to disable `-Wtype-defaults`
(setq haskell-process-args-cabal-repl '("--ghc-option=-Wno-type-defaults" "--ghc-option=-ferror-spans"))