Upgrade to Hyper 1.x

`hyper-util` uses `client-legacy`, an implementation from 0.14.x.

However, Hyper has had quite a few version bumps since then, and the latest is [v1.7.0](https://crates.io/crates/hyper) at the time of writing.

This will likely require connection pooling management on the client side, which is an advantage, as we can mitigate more potential KeepAlive issues with more aggressive stale sockets cleanup.

Moreover, perhaps a lot of old code related to HTTP streaming can be cleaned up or at least revisited.