For better auditing this PR adds a dashboard login event to the management service.
For that the user object was extended with a field for last login that is not actively saved to the database but kept in memory until next write. The information about the last login can be extracted from the JWT claims nb_last_login. This timestamp will be stored and compared on each API request. If the value changes we generate an event to inform about a login.
The new functionality allows blocking a user in the Management service.
Blocked users lose access to the Dashboard, aren't able to modify the network map,
and all of their connected devices disconnect and are set to the "login expired" state.
Technically all above was achieved with the updated PUT /api/users endpoint,
that was extended with the is_blocked field.
