[iOS][Translate] Refactors popup menu UI for reuse

- Removes dependency of :popup_menu_ui to the tools  popup menu and
  navigation popup menu logic, i.e., PopupMenuCommands, coordinator, and
  mediator, allowing it to be reused in the new translate infobar for the
  language selection as well as translate options popup menus.
- Moves reusable UI targets to ios/chrome/browser/ui/popup_menu/publicenu.

Bug: 910994
Change-Id: I16229bd0d8d64ba4e20498bdb3ea283b780f0678
Reviewed-on: https://chromium-review.googlesource.com/c/1358114
Commit-Queue: Moe Ahmadi <mahmadi@chromium.org>
Reviewed-by: Gauthier Ambard <gambard@chromium.org>
Cr-Commit-Position: refs/heads/master@{#615509}
35 files changed