Add script to reconcile keys and quotas in Redis.

[neprune]

For https://github.com/mysociety/sysadmin/issues/2125.

[neprune]

Dry run against live:

• 6 API keys in Redis with no DB record that would be deleted.
• 2 quotas in Redis with no DB record that would be deleted (seemed related to testing).
• All but 10 stripe subs were 'active'. These were 'incomplete_expired'. Most have active API keys and also quota set-up in Redis, but at least wouldn't have had their counts reset. I think this is because stripe isn't firing customer.subscription.deleted in this scenario and we're not checking the status in our 'updated' hook logic.

incomplete_expired scenario needs a proper look but for now just updating this script to delete these as it already does for canceled.