Remove unused inputs_id and params_id fields in SoftwareResult

These fields aren't actively used anywhere (and haven't ever been). So we should remove them. An additional PR that contains a migration to remove the db columns is forthcoming. 

````SQL
genome=> select count(*) from result.software_result where params_id is null and inputs_id is null;
  count
---------
 9907314
(1 row)

genome=> select count(*) from result.software_result where params_id is not null or inputs_id is not null;
 count
-------
     6
(1 row)
````