Provide a built-in way to limit number of sessions per user

Feature:
Provide a built-in way to limit the number of concurrent sessions per user

Description:
We want to limit our users to having only one session at a time. It would be nice to have this in Auth0 instead of having to build a custom integration with our API server using actions.

Use-case:
For security purposes, we want to limit our users to having only one active session at a time. When a new session is started, any existing sessions should be ended.