Rate Limiting / throttling

We currently support setting a concurrencyLimit on a task, or on a queue that you create. This can also be used with a concurrencyKey to have per-user queues: https://trigger.dev/docs/queue-concurrency

Sometimes instead of concurrency you want to limit using a rate. For example, 10/minute, 1/second.

This is especially useful when using APIs that have rate limits.

We should support this with a per-tenant key like we do for concurrency.