[Feature Request] Add command to close active fork session

Question

**Bug Description**
Add the ability to close a fork, for example /fork-close or /close

**Environment Info**
- Platform: darwin
- Terminal: pycharm
- Version: 2.1.195
- Feedback ID: 8ac7681c-0225-4b45-a18a-f277dfe0b369

**Errors**
```json
[]
```