Improve the flexibility and compatibility of OIDC integration

There are some OIDC providers that do not support for OIDC RP-Initiated Logout such as AWS Cognito. Therefore, when I try to integrate AWS Cognito with Nifi, the login function works well but the logout function does not. It would be nice if Apache Nifi could provide a way to configure OIDC more flexibly and compatibly with many OIDC providers. For example, in Apache Superset configuration (or Flask App Builder), it allows to enter ODIC configuration as the attached image. User can define authorize/request/refresh/logout URLs if they are not returned from 

https://<oidc_provider_host>/.well-known/openid-configuration

Or Nifi could add new properties to configure logout/refresh token URLs.