Consolidate logic in ScheduleSortingAttributes

[JasonFreeberg]

There's some redundant logic in the ScheduleSortingAttributes class. This can be moved out into a private method to keep code dry.

This is the redundant logic. This is copied in a few places.

 allTimesAndPlaces.forEach((TimeLocation timeLocation) ->
            timeLocation.getFullDays().forEach((DayOfWeek dayOfWeek) -> {
                // TODO: clean this up using Map.computeIfAbsent(...)
                if (groupedTimes.containsKey(dayOfWeek)) {
                    groupedTimes.get(dayOfWeek).add(timeLocation);
                } else {
                    groupedTimes.put(dayOfWeek, new ArrayList<>());
                    groupedTimes.get(dayOfWeek).add(timeLocation);
                }
            })
        );