added a new component for generating sample values for categorical columns (CategoricalSampleGenerator) and use it correctly for categorical columns in NumericSampleGenerator and TextGeneratorComponent;
skip histogram and quartiles computation for categorical numeric columns
I observed some additional bugs in ValuesWithCountList.GetRandomValue, which I will investigate and fix with a separate PR
CategoricalSampleGenerator) and use it correctly for categorical columns inNumericSampleGeneratorandTextGeneratorComponent;ValuesWithCountList.GetRandomValue, which I will investigate and fix with a separate PR