gleam: Formatter should not remove single-line breaks and should make multi-line ones into single-line.

Formatter should not remove single-line breaks, except for those within a multi-line expression. Also, it should make multi-line ones into single-line.

For example:

let a = "abc"

io.println(a)

should remain intact, while

let a = "abc"


io.println(a)

should be transformed into the former.

Meanwhile

iterator.from_list([1, 2, 3])
  |> iterator.first

  |> should.equal(Ok(1))

should be transformed into

iterator.from_list([1, 2, 3])
  |> iterator.first
  |> should.equal(Ok(1))