add InvalidCredentialsError with language-agnostic code (#15472)

* add InvalidCredentialsError with language-agnostic code and update backend & web logout logic

* error.code in API error responses

Updated the error handler to serialize responseErr.code as the JSON error field, falling back to responseErr.name when no code is set.

* fix(lint): whitespace and missing def

* fix(lint): missed one

* add InvalidCredentialsError case for bad token

Add test verifying that auth middleware throws InvalidCredentialsError with code "invalid_credentials" and correct translated message when the API token is invalid.

* fix(test): user fields implicitly required

---------

Co-authored-by: Kalista Payne <sabrecat@gmail.com>

website/server/middlewares/auth.js

@@ -2,6 +2,7 @@ import moment from 'moment';
 import nconf from 'nconf';
 import url from 'url';
 import {
+  InvalidCredentialsError,
   NotAuthorized,
 } from '../libs/errors';
 import {
@@ -81,7 +82,7 @@ export function authWithHeaders (options = {}) {
       .exec()
       .then(user => {
         if (!user || apiToken !== user.apiToken) {
-          throw new NotAuthorized(res.t('invalidCredentials'));
+          throw new InvalidCredentialsError(res.t('invalidCredentials'));
         }
 
         if (user.auth.blocked) {