Prevent invalid language choice errors

[mandolyte]

Today tc-create allows the user to select an org and resource and language combination that is not valid. When that happens this error is shown:

In this case: QA DCS, org: translate_test, resource type: any, language: vi

Once the org is known, the valid languages can be determined. In the case above the API call is:
https://qa.door43.org/api/v1/users/translate_test

Which returns:

{
  "id": 24384,
  "login": "translate_test",
  "full_name": "",
  "email": "",
  "avatar_url": "https://qa.door43.org/user/avatar/translate_test/-1",
  "language": "",
  "is_admin": false,
  "last_login": "0001-01-01T00:00:00Z",
  "created": "2020-06-18T17:22:49Z",
  "repo_languages": [
    "en",
    "hi",
    "kn"
  ],
  "username": "translate_test"
}

Notice that only three languages are being used: "en", "hi", and "kn". So in this case I would not have been able to select "vi" in the first place and thus could have avoided the error (which doesn't come until you select a file to edit/translate).