Allow comments in the middle of `|>` pipelines

Allowing comments in the middle of `|>` pipelines would be very useful

```mint
component Main {
  fun render : Html {
    let sum =
      [1, 2, 3]
      |> Array.map((i : Number) { i * 2 })
      // |> Array.select((i : Number) { i % 3 == 0 })
      |> Array.reduce(0, (acc : Number, i : Number) { acc + i })

    <div>"#{sum}"</div>
  }
}
```