Improve configuration of ModeAvailability

[sebhoerl]

Currently, we have two ModeAvailability implementations: DefaultModeAvailability and CarModeAvailability. I would propose that this is unified into DefaultModeAvailability, which gets two additional flags through the config file:

• considerLicense
• considerCarAvailability

Maybe then we could add a more flexible ModeAvailability where the use of modes can be controlled by config groups (and maybe person attributes).