Use config to decide the 'sub-geography' to use #344
Description
After @tomjemmett added ICBs to the lookup in #343 and demonstrated results for an ICB in the outputs app, I said:
i suspect we'll head towards a new metadata element [in params.json] called 'geography' or something (scheme, icb, etc) that can help control what's shown in the 'site selection' box
Tom suggested:
what I did for the ICB model is shoved the dataset column into the sitetret column, maybe long term would be better to drive this by config and keep column names sensibly named
So if we're looking at results for a scheme, it would lookup in the config that the sub-level of 'scheme' is 'site', which would then be shown in the dropdown selection box in the app. And so on for other geographies.