[Stats results mapper] - Include viability category field on final stats_results_parquet

[francisco-ebi]

I noticed that in the function that generates the viability_stats dataframe (viability_stats_results) is already picking the correct field(the viability statement) based on the VIA parameter version. So it would only be a matter of propagating the field through the intermediate parquets.

So I updated 2 stages of the statistical results mapper to make the "category" field available on the final statistical_results parquet:

• Updated the 1st stage (manual phenotype calls processing), when the viability dataframe is updated based on the columns of the stats_analysis_out_parquet, I added the missing "category" field.
• Updated the last stage (generate doc_id and final output), before the stats_results dataframe is saved to disk, I have added the category field to stats_results_column_list

Let me know if I have missed anything.