Title: [OAuth2] return 401 instead of 302 on xhr requests

Description:
In the context of Single Page Application (SPA) the code is stored in cache in the browser and at the end of the session having a 302 redirect will cause issue in the design. Typically when xhr request is detected it should return 401 instead.

Is it such configuration possible ? I try to search on the documentation but was not able to found it.

[optional Relevant Links:]
Example on another auth-proxy
Oauth2-Proxy: https://oauth2-proxy.github.io/oauth2-proxy/docs/behaviour/
Specific line:
"If authentication is required but missing then the user is asked to log in and redirected to the authentication provider (unless it is an Ajax request, i.e. one with Accept: application/json, in which case 401 Unauthorized is returned)"

Thanks for the help