Improve the preprocessor.py

The current preprocessor.py (which creates augmented exposure models) in the utils directory is very slow and can take up to 15 days to create the augmented exposure model for an exposure model of 17 million assets.

The preprocessor.py should be modified to create the augmented exposure models in database or/and csv format. It will execute much faster and it gives the losscalculator the opportunity to later take the exposure as database format and not slow csv files.