New report field formulas

Our idea of user experience on Datoris directs us towards a single page self service application that doesn't require prior data science knowledge. However, we want to provide more advanced features to more proficient users. In this update, we've introduced distinct and concat types of field aggregations. Predefined formulas are just a basis, we can extend them based on customer's needs. User can write their own transformations and combine fields using SQL-like syntax.