Merge branch '511-room-order++' into 'develop'

src/api/serializers.py

src/api/views/rooms.py

...ckoffice/templates/backoffice/schedule_source-detail.html

...e/templates/backoffice/schedule_source_import-detail.html

src/core/admin.py

src/core/models/links.py

src/core/models/rooms.py

src/core/models/schedules.py

src/core/models/shared.py