Command - Add Absence/LOA

Ask the person how long etc. and then post in the correct format.

Format:
```
[name]
[start date] - [end date]
[reason]
```

To do:
- [ ] Create MySQL Database Schema
- [ ] Integrate `!absent` command into Heimdall
- [ ] Create Windows App for viewing absentees
- [ ] Integrate `!absences` command into Heimdall

The issue describes adding absence/leave of absence commands to a Discord bot named Heimdall. First, examine the existing bot command structure, likely in a commands directory. Then, design a MySQL schema for storing absences with fields for name, start date, end date, and reason. Implement the `!absent` command to collect user input and store it, and the `!absences` command to retrieve and display the data. Finally, consider how the Windows app for viewing absentees would interact with the database.

Scritto dal modello di indicizzazione a partire dal testo della issue.