text: Title: Add `include_columns` option to `create_pydantic_model`
  Body: `create_pydantic_model` has an `exclude_columns` argument, but it would be very useful to also have an `include_columns` argument.
  
  If neither are specified, all columns are returned. If both are specified, then an exception is raised.
  
  ```python
  class Band(Table):
      name = Varchar()
      popularity = Integer()
      # Imagine it has lots more columns ...
  
  model = create_pydantic_model(include_columns=(Band.name,))
  ```