Add option to ignore keys/columns when loading a dataset from jsonl(or any other data format)

### Feature request

Hi, I would like the option to ignore keys/columns when loading a dataset from files (e.g. jsonl).

### Motivation

I am working on a dataset which is built on jsonl. It seems the dataset is unclean and a column has different types in each row. I can't clean this or remove the column (It is not my data and it is too big for me to clean and save on my own hardware).
I would like the option to just ignore this column when using `load_dataset`, since i don't need it.
I tried to look if this is already possible but couldn't find a solution. if there is I would love some help. If it is not currently possible, I would love this feature

### Your contribution

I don't think I can help this time, unfortunately.