Add prompter's hyperparameter to sigllm/core.py

* sigllm version:
* Python version:
* Operating System:

### Description

Add frequently used hyperparameters of prompter pipeline to sigllm/core.py, so users can easily change them.

### What I Did

```
Paste the command(s) you ran and the output.
If there was a crash, please include the traceback here.
```
