More CLI to make nextflow pipeline python scripts no longer needed

[JudithBernett]

Right now, we have a lot of python scripts in the nextflow pipeline. Would be nice if they would no longer be needed and we could just call, e.g., drevalpy make hpamsplits, drevalpy make finalsplits, drevalpy runcv, …

[JudithBernett]

If using something like Typer or Click it should be pretty easy - basically just adding decorators to existing functions (or maybe having a wrapper script that calls the functions).