Implement GET /functions/v1/events/{event_id} endpoint

[tjhiaj]

Sample response:
{
"event": {
"id": "1e33aa34-fd82-4e8e-a685-3124452dfeab",
"title": "Women in Tech Panel",
"description": "...",
"start_time": "2025-03-12T18:00:00-05:00",
"end_time": "2025-03-12T20:00:00-05:00",
"location": "IC Atrium, UTSC",
"banner_url": "https://..."
}
}