Add EntityListAlign to imports step

[sorki]

This patch add support for alignment of lists of constructors, class methods, fields names in import lists entities.

ELMultiline causes

import Foo (Bar(x, y))

To be expanded to

import Foo
  (Bar
    ( x
    , y
    )
  )

This is useful in combination with LongListAlign Multiline to get a git friendly formatting.

[sorki]

A less contrived (and prettier) test requires #468 for forcing multiline only output, which causes the output to look like:

import Linear
  ( V2(V2)
  , V3(V3)
  , V4(V4)
  )

import Prelude
  ( Bool(True)
  , Eq((==))
  , Num 
      ( (*) 
      , (+) 
      )   
  )

The special case of single entity is needed to prevent

import Linear
  ( V2
      ( V2
      )
  , V3
      ( V3
      )
  , V4
      ( V4
      )
  )

This in combination with #468 allows for the most git-friendly formatting when explicit import lists are used (typically when -Wmissing-import-lists is enabled).