[ios clean] Moves animator and presenters under transitions

ios/clean/chrome/browser/ui/transitions/presenters/BUILD.gn

 # Copyright 2016 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 source_set("presenters") {
   sources = [
     "menu_presentation_controller.h",
     "menu_presentation_controller.mm",
     "menu_presentation_delegate.h",
   ]
 
   configs += [ "//build/config/compiler:enable_arc" ]
 
   deps = [
     "//ios/clean/chrome/browser/ui/commands",
   ]
 }