Onboard Smogon onto @pkmn/stats

[scheibo]

Tracking issue to determine work that needs to be done to help Smogon migrate away from https://github.com/smogon/usage-stats and onto a process using @pkmn/stats:

• Update tiering banlist information #5
• Update hardcoded sets of Formats utils to be computed programmatically from PS data #9
• Implement simple logs processing loop that is suitable for processing large amounts of usage stats #11
• Refactor tier update reports #12
• Make sure all updates to smogon/usage-stats are reflected in @pkmn/stats #13

For the migration process, there are a number of stages:

• local validation: reports run well locally over logs corpus and produce desired results
• manual remote validation: reports can run on sim3 and produce the desired results
• automated remote validation: reports are set up to run daily via cron and at the end of the month the results match the expected result

Smogon may choose to remove the old code after manual remote validation is complete, but from pkmn's perspective onboarding will not be considered complete until Smogon is confidently running this code in a hands off manner