Add a Manage Labor to the event page

- On Edit event, in manage volunteers, we are going to implement two more columns: "labor" and "volunteer service" checkboxes which are mutually exclusive. There should be a count of hours for either one of the checkboxes checked or for just participation with no labor or service hours.
- "Add volunteers" button should be renamed to "add participants"
- Add an X for deleting participants in the modal when you added one and want to remove it in the modal.
- When we calculate RSVP and waitlist, they should not be added as labor
- Add to "eventparticipant" model new columns in database: isLabor, isService
- When we calculate RSVP and waitlist, they should not be added as labor