New default DNS resolver

[aajtodd]

Implement/change default DNS resolver behind a new behavior version for the default HTTP client.

We've had a number of issues around scaling and DNS. The default implementation in hyper-util uses blocking GAI (get address info) call on every request, relying on the OS for caching.

We would want a new resolver that:

1. Handles caching in-memory by default
2. first class async support
3. minimal footprint
4. Automatic rotation
5. A way to report connection errors back to resolver to de-prioritize or temporarily remove records from being yielded by the resolver
6. possible static round-robin support/alternative

See also:

• V1577493841
• Add support for hickory-dns for http client dns resolution #3962