Accept timedelta window_size in cutoff_window_sequences

[csala]

The primitive mlprimitives.custom.timeseries_preprocessing only accepts integers as window_size specification:

https://github.com/HDI-Project/MLPrimitives/blob/a592c8446aa614cd9d0eb6c73735d11ebc876129/mlprimitives/custom/timeseries_preprocessing.py#L216

This should be made flexible, so pd.Timedelta objects or the corresponding str specifications can be passed.

As an example, if an X is passed where the time index has a regular frequency of one hour (so, there are 24 data points every day), all these window_size values should be equivalent:

• 24
• '24h'
• '1d'
• pd.Timedelta(hours=24)
• pd.Timedelta(days=1)