* extends user and group structure by introducing fields for issued and integration references
* Add integration checks to group management to prevent groups added by integration.
* Add integration checks to user management to prevent deleting user added by integration.
* Fix broken user update tests
* Initialize all user fields for testing
* Change a serializer option to embedded for IntegrationReference in user and group models
* Add issued field to user api response
* Add IntegrationReference to Group in update groups handler
* Set the default issued field for users in file store
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.
