Feature: Insert event through slash command

- [ ] Log reminding deadline event. (2 week, 1 week, 2 days, 1 days before the event)
- [ ] Create event in google calendar with input like this:

# Input: 
```
/update-event 
@param Người phụ trách: Họ và tên
@param Time: dd/mm/yyyy hh:mm z (time zone UTC)
@param Content: "hôm nay buồn quá  link("https://fap.fpt.edu.vn/Schedule/ActivityDetail.aspx, ....) ".
```

Est: 8h