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

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

website/server/middlewares/errorHandler.js

@@ -82,7 +82,7 @@ export default function errorHandler (err, req, res, next) { // eslint-disable-l
 
   const jsonRes = {
     success: false,
-    error: responseErr.name,
+    error: responseErr.code || responseErr.name,
     message: responseErr.message,
   };