Refactoring users, groups and announcements

[Metawolve]

We should refactor the users, groups, and announcements records for EF30.

Currently, we have user records, IdentityAnnouncementGroups, and user groups as a json column in the UserRecord.

Nicer would be having 3 tables:

• Users
• Groups
• Announcements
• DeviceIdentities

And relating these like this:

• Users n:m Groups
• Announcements n:m Groups
• User 1:n DeviceIdentities

Also, the function that adds new users to the database is currently triggered by another function called "ReadRegSys" which is not very readable, a better way would be e.g. using the UserService from the RoleClaimsTransformation or from another middleware.

Possibly, user groups will be removed in the future if we get a better way to query user groups from the IDP during runtime, when an announcement for specific groups is being created.

We should further discuss how we can improve the current model.