Clarify volunteers earning student hours vs labor hours vs participants

Refactor on handling volunteers vs. participants vs. labor, make the distinction clear at the top of the edit/manage event page. It should be clear that volunteer opportunities are all opportunities/events that earn service hours. Volunteer opportunities, trainings, education/engagement, and bonner scholar events are all mutually exclusive. They can be mixed with labor or not. Labor can be a category by itself when creating an event, like in labor meeting event.