Handle 429 responses when streaming data

* It's standard for public tile servers to have a IP-based rate limit over a sliding window of time and return a 429 code when that limit is reached.
* Ideally, anywhere we stream data we would have a backoff strategy in place to successfully retry when encountering a 429.

The issue names no files, tests, or entry points. Start by locating the code paths that stream data and handle HTTP responses, then inspect how retries are currently performed. Done means streaming requests that receive HTTP 429 responses use a backoff strategy and can retry successfully.

Written by the indexing model from the issue text.