Add a new daily job to build Covid Recovery Dash data.json

[idreyn]

Some plans are forming around the Covid Recovery Dash:

• In the immediate term, we'd like to automatically update it daily
• In the medium term, we want to port its functionality over to the System Ridership tab of the Data Dashboard

In either case, the first step is to generate the CRD's data.json file from our ScheduledServiceDaily and Ridership Dynamo tables. An example of the file is here, and the code that generates it is here. With the daily ridership and service level data already available in Dynamo, there's a lot of logic from the CRD codebase that can be dropped or ignored — the important thing is that the structure of the file should remain the same.

In the end, we should have a cron job in this repo that automatically updates this file daily, running shortly after the tables mentioned above are updated, and drops it somewhere in S3. We will probably want to beef up the lambda_timeout and lambda_memory_size for the job to make sure it can reliably complete — it's got a lot of work to do. We should also consider parallelizing Dynamo reads if possible, since it'll need to look up values for ~100 routes.

Nice-to-haves:

• We'd prefer to have the file contain pre-covid history too, perhaps back to 2016
• If the file is getting very large, we should consider chunking it by route
• If you can add ridership and service breakdowns by mode while you're in here, please do! There's already a spot for system-wide values that this can slot into nearby.