feat: fetch single event with all attendees #45

[estherbreath]

New Controller Method:

• Created the fetchSingleEventDetails method to:
  • Fetch event details by event_id.
  • Include attendees from the attendees field.
  • Return a success or failure response based on the outcome.

New Endpoint:

• GET /:event_id/details: Fetch event details along with attendees.

Error Handling:

• Returns a 404 Not Found if the event does not exist.
• Handles server errors with appropriate 500 Internal Server Error responses.