Improve printing of callbacks in promise chains

[IwanKaramazow]

https://forum.rescript-lang.org/t/weird-auto-code-formatting-with-pipe-first-operator/1189

let myPromise = Js.Promise.make((~resolve, ~reject) => resolve(. 2))

myPromise->Js.Promise.then_(value => {
  Js.log(value)
  Js.Promise.resolve(value + 2)
}, _)->Js.Promise.then_(value => {
  Js.log(value)
  Js.Promise.resolve(value + 3)
}, _)->Js.Promise.catch(err => {
  Js.log2("Failure!!", err)
  Js.Promise.resolve(-2)
}, _)

Now, if I try to put some comments in those anonymous functions, you get the same (seemingly) weird code-fomatting thing going on.