City level daily totals data dump

[cutepig]

Closes #299

City level daily totals data dump

• Adds new city_level_daily_totals.json open data file
• Adds healthcare_contact field to city and postal code sets
• Fixes null-field issues with accumulated data
• Postal codes/cities are filtered as in city-level general results:
  • Postal codes are mapped using low_population_postal_codes.json
  • Postal codes and cities not found in population_per_city.json are ignored

[cutepig]

On a side note, in the postal code json files, is there a reason for using dev url instead of prod as the link in metadata section? 🤔 https://github.com/futurice/symptomradar/blob/master/infra/modules/main/open_data/low_population_postal_codes.json#L5

That's a really good catch! You're indeed correct here, and we should probably change all those url's in the static JSON files to point to prod. The tricky thing though is when we generate the index JSON, we should change those urls to point to the correct domain since that field is just pulled from the JSON metadata itself.

[cutepig]

I'll merge this in now, and fix the JSON URL's in another PR.