Add robust scaling preprocessor

[LouisCarpentier42]

Add a robust scaler to the preprocessing module. This scaler is similar to the z-normalization, but more robuust against outliers. While Z-normalization uses the mean and standarddeviation to normalize the data to have 0 mean and unit std, robust scaler uses the median and inter quartile range to normalize the data instead. This means it is less affected by outliers.