Clarify ambiguous HTTP return code

https://github.com/eclipse-ee4j/jersey/blob/7b6d2f84391f24310baae7d8e55e644703642826/core-server/src/main/java/org/glassfish/jersey/server/filter/RolesAllowedDynamicFeature.java#L55-L56

The specification of the expected HTTP status code is ambiguous. `403 (Not Authenticated)` does not exist in [RFC 7235](https://www.rfc-editor.org/rfc/rfc7235). It should be either `403 (Forbidden)` or `401 (Unauthorized)`.

According to [RFC 7235](https://www.rfc-editor.org/rfc/rfc7235) ...
> A server that receives valid credentials that are not adequate to
gain access ought to respond with the 403 (Forbidden) status code

> The 401 (Unauthorized) status code indicates that the request has not
been applied because it lacks valid authentication credentials for
the target resource.

... 401 (Unauthorized) might be the appropriate/intended return code.

Read RolesAllowedDynamicFeature.java at the linked lines, then compare the behavior with the cited RFC 7235 definitions for 401 and 403. Determine which authentication state the role check represents; done means the chosen status code and its specification-facing wording are no longer ambiguous.

Written by the indexing model from the issue text.