use flask-native global configuration

Project description: Every Flask app has a .config attribute to store configuration. Additionally, for MSColab/MSWMS we have mscolab_settings/mswms_settings. This is redundant, we could just use app.config for everything that should be made globally available in the application in a key-value fashion.
Duration: 175-350h
Skills: Python, flask, pytest Git, AI-Assistant
Difficulty level: Medium
Related Readings/Links:
- https://github.com/Open-MSS/MSS/issues/2506
- https://github.com/Open-MSS/MSS/issues/2442
- https://flask.palletsprojects.com/en/3.0.x/patterns/appfactories/
Potential mentors: m.risse@fz-juelich.de, rb.proj@gmail.com