Add i18n support to Select-to-speak

chrome/browser/resources/chromeos/select_to_speak/manifest.json.jinja2

 {
 {%if key is defined %}
   "key": "{{key}}",
 {% endif %}
   "manifest_version": 2,
-  "name": "TODO: Translated Select to speak name",
+  "name": "__MSG_SELECT_TO_SPEAK_NAME__",
   "version": "{{set_version}}",
-  "description": "TODO: Translated Select to speak description",
+  "description": "__MSG_SELECT_TO_SPEAK_DESCRIPTION__",
 {% if is_guest_manifest == '1' %}
   "incognito": "split",
 {% endif %}
   "background": {
     "scripts": [
       "select_to_speak.js"
     ]
   },
   "permissions": [
     "accessibilityPrivate",
     "tts"
   ],
   "automation": {
     "desktop": true
-  }
+  },
+  "default_locale": "en"
 }