Store an exercise lists sort type and make sure the list applies that sort type

The exercise list should know what type of sort is applied to it so that the list opens to the last used sort.

Acceptance criteria

• Adjust the ExerciseList model to store the sort type
• Adjust the exercise list view to apply the sort type based on what's stored in the model
• Write using ExerciseList.Service (I'm trying to keep all writes to the database on a background actor)