Basic functionality for OMOP databases

Datafaker has interactive generator configuration, which now has a very powerful set of generators for Entity-Attribute Values, called Null-Partitioned Grouped generators. These can be used to generate fake data from a table such as OMOP's Measurement and Observation tables.

These generators match the real data in that the concept for the row determines what other values are possible for the non-numeric columns, the distributions for the numeric columns and the pattern of NULLs.