Implements parameterize_extract_columns + a dataframe API

This provides a convenience API for
#196. The idea is that
people want to do a parameterization and extract columns operator at
once -- this should be easy. The cool thing is that this just uses the
parameterize and extract APIs. It also has a from_df() function to allow
for passing in a dataframe to be more concise.

hamilton/function_modifiers/expanders.py

@@ -479,6 +479,7 @@ def dict_generator(*args, **kwargs):
             return dict_generated
 
         output_nodes = [node_.copy_with(callabl=dict_generator)]
+
         for field, field_type in self.fields.items():
             doc_string = base_doc  # default doc string of base function.