Move all files under `operators/dialogue` to `operators/conversations`

### Reminder

- [x] I have read the above rules and searched the existing issues.

### System Info

N/A

### Reproduction

```text
Put your message here.
```


### Others

Move this file https://github.com/OpenDCAI/DataFlow/blob/main/dataflow/operators/dialogue/consistent_chat.py to `conversations`.