Change indendtation of functions with many arguments

Current indentation:

let makeCallback =
    (
      ~target,
      ~method,
      ~getHeader,
      ~create_response,
      ~respond_with_string,
      ~headers_of_list,
      ~read_body,
      ~headers,
      ~context: Context.t,
      reqd,
    ) => {
  open Lwt.Infix;

What I want (and more people on Discord seem to agree):

let makeCallback = (
  ~target,
  ~method,
  ~getHeader,
  ~create_response,
  ~respond_with_string,
  ~headers_of_list,
  ~read_body,
  ~headers,
  ~context: Context.t,
  reqd,
) => {
  open Lwt.Infix;

With my proposal the body of the function is in line with the arguments instead of to the left of them.

Start by locating the formatter logic that handles functions with many arguments, using the OCaml examples in this issue as a reproduction case. Run the formatter on the example and verify that the opening parenthesis and arguments are indented as shown while the function body aligns with them.