Functionality to give column index as fh args instead of column names

[samrudh]

I would like to use same fh_args for different dataframe
For compatibility of the template with other dataframe, I would like to give fh_args based on column index.

Like mentioned below
'_sort': [df.columns[1]] }

[jaidevd]

@samrudh please see if you can make the necessary changes in nlg.search.set_fh_args to make this work.