Bug: `type-decl=sparse` is ignored in type extensions

[Invizory]

Bug Description

If type-decl=sparse option is set, ocamlformat does not break lines between constructors in type extensions.

How to Reproduce

.ocamlformat:

profile = default
version = 0.28.1
type-decl = sparse

example.ml:

type s =
  | A
  | B

type t = ..
type t += C | D

$ ocamlformat example.ml

Actual result:

type s =
  | A
  | B

type t = ..
type t += C | D

Expected result:

type s =
  | A
  | B

type t = ..
type t +=
  | C
  | D