Starts an exercise (HKWorkout) and stream to iOS Companion
func startExercise(forType workoutType: WorkoutTypes, completion: @escaping(Bool, TerraWatchOSError?) -> Void))
workoutType: WorkoutTypes-> The workout type Enum to start exercise for@escaping(Bool, TerraWatchOSError?) -> Void)-> Completion function signifying when the exercise started correctly or not