Format imports qualified post

Starting from GHC 8.10, with this extension enabled, one can write:

```haskell
import A qualified
import B
import C
```

Now we can save 10 spaces on non-qualified imports!

```haskell
module Bad where

import Control.Applicative ((<$>))
import System.Directory    (doesFileExist)

import Data.Map            (Map, keys, (!))
import Data.Map            qualified as M
```