Investigate Cloudflare ratelimit api

[laggycomputer]

Instead of the chopped system we have now.

Will need to bump Wrangler and navigate dependency hell.

[laggycomputer]

This is not as promising as thought.
So far:

1. Ratelimits are local to location.
   A global ratelimit becomes impossible.
2. A ratelimit binding, which contains a single map from a ratelimit key to a cooldown bucket, has exactly one cooldown policy.
   So overriding the rate limit for individual keys becomes impossible.
   The best we can do is put certain keys in a super special bucket, but this would require a KV call, right back where we started.
3. The cooldown policy is expressed in requests per 10 or 60 seconds.
   The existing per-hour policy is not possible.