bin/sort sorts private as though it were a method

private and protected shouldn't be sorted by bin/sort.

Input:

module Foo
  def baz: (*untyped) -> untyped

  private

  def foo: (*untyped) -> untyped

  def bar: (*untyped) -> untyped
end

Output:

module Foo
  private

  def bar: (*untyped) -> untyped

  def baz: (*untyped) -> untyped

  def foo: (*untyped) -> untyped
end

What I'd expect the output to look like, with the private methods sorted within themselves:

module Foo
  def baz: (*untyped) -> untyped

  private

  def bar: (*untyped) -> untyped

  def foo: (*untyped) -> untyped
end

Start by reading and running bin/sort with the RBS input shown in the issue. Check how visibility declarations are classified during sorting, then verify that public methods remain separate and methods under private or protected visibility are sorted within their own section.