add support for additional aggregations by time period and other geographies

[critzo]

Logging some ideas from conversation with a developer who integrates our data using BQ now. These could be future additions to the stats-pipeline, or could be fulfilled by producing examples using the existing planned statistics:

Geographies:

• State (v0)
• County (v0)
• County Subdivision (FUTURE)
• Census-Defined Place (FUTURE)
• Tribal Areas (FUTURE)
• School districts (unified, secondary, elementary) (FUTURE)
• Congressional districts (FUTURE)
• State legislative districts (upper, lower) (FUTURE)

Example time period aggregations:

• day
• week
• month
• quarter
• year

[critzo]

Aggregation by any of the time periods above is possible using the current output. By querying the stats tables in BigQuery, we can add summary statistics over any day, week, month, quarter, year, or multi-year.

For example, the query below would provide stats for US counties in the first quarter of 2021:

WITH
mlab_us_counties AS (
	SELECT * FROM `measurement-lab.statistics.v0_us_counties`
	WHERE date BETWEEN '2021-01-01' AND '2021-06-30'
)
SELECT 
	MIN(download_MIN) AS download_MIN,
	AVG(download_MED) as download_MED,
	MAX(download_MAX) AS download_MAX,
	MIN(upload_MIN) AS upload_MIN,
	AVG(upload_MED) AS upload_MED, 
        MAX(upload_MAX) AS upload_MAX,
	county_fips_code,
  county_name
FROM mlab_us_counties
GROUP BY county_fips_code, county_name