Group buildings into campuses

[ChristophWurst]

As an admin of a university Nextcloud, it would be helpful to optionally group buildings into campuses. This information can be picked up by the Calendar front-end.

Technical details

This needs a new table and entity. When a building is created there should be an optional argument for a campus ID.

[ChristophWurst]

Remain questions

• How to handle buildings without campuses?
• Does the Calendar search have to filter by campus?
• How to display the campuses in the Calendar search results

[miaulalala]

Preliminary To Do:

• add new table for campuses
• update building table
• Possibly add fields to the IRoomMetadata class
• write occ command to create a campus