Return OIDC code flow error_code and error_description directly to the user if no error handler is available

[sberyozkin]

Description

If the OIDC code flow fails, then a user can point to to an error handler endpoint with quarkus.oidc.authentication.error-path. Error handler can provide a nicely formatted page, and suggest a user to retry by following some link, etc.

If the error handler is not available, 401 is returned. But it would be better return the error code and description directly to the user as a simple text message. Users can see them in the browser URL but it is not easy

Implementation ideas

Return a text message including the error code and description if no error handler is available

[quarkus-bot]

/cc @pedroigor (oidc)