Split AKModel views into different files & introduce modular status page
- Move AKModel views into several subfiles to improve overview and resolve problems with circular imports
- Introduce new modular status page handling (widgets and views)
- Port main status page to new structure
- Move AK messages status page visualization to AKSubmission (therefore, they automatically do not show up when there is no possibility to create them)
- Introduce status widget for virtual rooms
- Fix timezone issue for rendering of AK messages on status page
- Adapt status page URL in several views and tests
This lays the foundation for #105