Change invalid auth to return 401
For each request, the USS-API uses the [DrupalOAuthService](https://gitlab.eclipse.org/eclipsefdn/it/api/eclipsefdn-api-common/-/blob/main/efservices/src/main/java/org/eclipsefoundation/efservices/services/DrupalOAuthService.java) to validate tokens. This service returns 403 errors. The USS endpoints should instead return a 401. [A custom exception](https://gitlab.eclipse.org/eclipsefdn/it/api/eclipsefdn-api-common/-/blob/main/core/src/main/java/org/eclipsefoundation/core/exception/UnauthorizedException.java) has been added to facilitate this change.
issue