Add indicator for upcoming homeworks in the timetable (feature request)

[nilsreichardt]

Description

A user requested to see the homework in the timetable. We could show an indicator for a lesson when a homework should be done until this lesson.

We need to discuss if we want to implement and if yes, how exactly the feature looks like with all edge cases.

[Lauritz-Tieste]

Please add for this Feature a function to disable the indicator in the settings