Add an option to vertically format imports

[jonaprieto]

I was wondering if stylish haskell has currrently some way to have the imports with the next layout:

import OnlineATPs.Defaults    ( getDefaults )
import OnlineATPs.Options
  ( Options
    ( optATP
    , optHelp
    , optATPList
    , optTime
    , optVersion
    , optInputFile
    )
  , processOptions
  , printUsage
  )

With the settings by default I have this output:

import           OnlineATPs.Defaults (getDefaults)
import           OnlineATPs.Options  (Options (optATP, optATPList, optHelp, optInputFile, optTime, optVersion),
                                      printUsage, processOptions)

[neongreen]

Btw, you already can get multiline imports: https://github.com/jaspervdj/stylish-haskell/blob/master/data/stylish-haskell.yaml#L67-L88.