[Refactoring] Refactor the schedule to use the stream repository

**Is your feature request related to a problem? Please describe.**
The schedule uses the CourseRepository class which needs to be removed. The schedule should use the CourseActivitiesRepository to use the new BaseStreamRepository class

**Describe the solution you'd like**
That the day, month and week viewmodels use the CourseActivitiesRepository class to retreive data
