For Translate, allow users to use the English name of the language or ISO 639 code to find the language.
I am a Chinese speaker. In Chinese, "English" is "英文" (England text) or "英語" (England speech). In real life, both have the same meaning. So I cannot use Chinese to search for the language even if the UI is set to Chinese because I don't know which word the UI uses.
I hope I can use the English name to search for the language even if the UI is not set to English.
I also want to use ISO 639 code to search the language. It is simpler than the full name. Most languages can be identified by 2 char (en/zh/jp/etc).
