get https://api.ottolearn.io/v1/rest/Mastery.ListUserActivities()
Returns a list of all assigned Activities for a specified User's Concepts. If a Concept has no assigned Activities, an empty array is returned. Each Activity returned will contain the Activity Draft Id, Id, Concept Id, identifier, the estimated duration, status, the rank for sorting of Activity itself and the Activity type Id. If a User ID is not provided then it will return the results for the authenticated User ID.