ui: Move strings translations out of ui/base.

ui/base/strings/BUILD.gn

-# Copyright 2014 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.
-
-import("//tools/grit/grit_rule.gni")
-
-# Meta target that includes both ui_strings and app_locale_settings. Most
-# targets want both. You can depend on the individually if you need to.
-group("strings") {
-  deps = [
-    ":ui_strings",
-    ":app_locale_settings",
-  ]
-}
-
-grit("ui_strings") {
-  source = "ui_strings.grd"
-}
-
-grit("app_locale_settings") {
-  source = "app_locale_settings.grd"
-}