Add an API endpoint to refresh users roles

To make sure we don't end up with stale role data in `smart-home-auth`, it would be good to have an endpoint that we can use to refresh the current roles of a `person`.

Currently we only get roles on receipt of a new JWT, which is usually when a user logs in. If a user keeps their session alive for a long time/doesn't log in our role data can get stale very quickly.

Example: A `person` is granted guest access to a door, and they log on and setup their keycard/phone. If they then don't interact with `smart-home` for a year, their role data stays stale. They can still open the door as their roles are not refreshed unless they log in again. We have no way of obtaining updated roles.