Random rows
Add a new endpoint: `/rows`

Parameters: `dataset`, `config`, `split`, `offset` and `limit`. 

It returns a list of `limit` rows of the split, from row idx=`offset`, by fetching them from the parquet files published on the Hub.

Replaces #687 
Random rows: Add a new endpoint: `/rows`

Parameters: `dataset`, `config`, `split`, `offset` and `limit`. 

It returns a list of `limit` rows of the split, from row idx=`offset`, by fetching them from the parquet files published on the Hub.

Replaces #687 